Use of remote ischemic conditioning to improve outcome after myocardial infarction

ABSTRACT

The invention provides methods for reducing the incidence and/or severity and/or delaying the onset of heart dysfunction/failure and improving overall survival through the use of remote ischemic per-conditioning and post-conditioning.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 61/319,597, filed on Mar. 31, 2010, entitled “USE OF REMOTE ISCHEMICCONDITIONING TO REDUCE HEART DYSFUNCTION AND/OR HEART FAILURE AFTERMYOCARDIAL INFARCTION”, the entire contents of which are incorporated byreference herein.

BACKGROUND OF THE INVENTION

Survivors of myocardial infarction (MI) are at significant risk of heartdysfunction/failure resulting from myocardial remodeling resulting fromthe MI. This remodeling is associated with poor long-term prognosis,with patients with post-MI congestive heart failure reportedly at a10-fold higher risk of death as shown in a 5 year follow up study.Treatment of myocardial infarction has concentrated on reducing theperiod of ischemia and minimizing injury that occurs duringpost-ischemic reperfusion. Thus, many therapies have aimed to reduce thesize of the heart infarct as much as possible or to prevent itsoccurrence altogether. Recently, deliberate and transient ischemicpre-conditioning has been proposed in order to reduce the effects ofischemic heart injury such as occurs with MI. It has been postulatedthat this pre-conditioning may essentially induce tolerance in the hearttissue to a later ischemic event such as MI, by reducing the infarctsize and thus resulting in a better prognosis.

SUMMARY OF THE INVENTION

The invention relates generally to the use of remote ischemicconditioning (RIC) to reduce the occurrence and/or severity and/or delaythe onset of heart dysfunction/failure associated with MI. The inventioncontemplates the use of RIC on a subject that is experiencing or hasexperienced an MI. RIC may be performed before and/or during and/orafter and MI provided that at least one RIC (including the only RIC) isperformed during or after the MI. The invention further contemplatesthat, in some instances, the subject will undergo more than one RICregimen. In some important embodiments, the invention contemplatesperforming RIC on a subject during, or after, or during and after an MI.The RIC is performed repeatedly, in some embodiments, including at leastonce during the MI and daily, every other day (i.e., every second day),every third day, or every fourth day thereafter for at least 10 days, atleast 20 days, at least 28 days, at least 30 days, or longer.

Thus, in one aspect, the invention provides a method comprisingperforming a repeated RIC regimen on a subject during and/or after anMI. The method may be a method for improving the overall outcome of asubject following MI, including but not limited to reducing the risk ofheart dysfunction/failure following an MI, reducing the incidence,frequency and/or severity of the symptoms associated with heartdysfunction/failure following an MI, and/or delaying the onset of heartdysfunction/failure or its associated symptoms, including but notlimited to exercise limitation, arrhythmia, and sudden unexpected deathfollowing MI. These methods comprise, in another aspect, performing arepeated RIC regimen on a subject having an MI, wherein a first RICregimen is performed during and/or after (including shortly after) theMI and one or more subsequent RIC regimens are performed at least every7, every 6, every 5, every 4, every 3, or every 2 days, or every dayafter the first RIC regimen.

In one aspect, the invention provides a method comprising performing arepeated RIC regimen on a subject having an MI, wherein a first RICregimen is performed during the MI and subsequent RIC regimens areperformed daily after the first RIC regimen.

In one aspect, the invention provides a method comprising performing arepeated RIC regimen on a subject that has experienced an MI. In oneembodiment, the subject has been given an RIC regimen during the MI orwithin 36 hours, within 24 hours, within 12 hours, within 6 hours,within 3 hours, within 2 hours, or within 1 hour of the MI, optionallylocally or remotely.

In one aspect, the invention provides a method comprising performingrepeated RIC regimens on a subject after an MI. In some embodiments, therepeated RIC regimens are commenced within 1 week or within 1 month ofthe MI. In some embodiments, the subject has not undergone priorischemic conditioning during the MI.

In some embodiments, the subject has not undergone ischemic conditioningprior to the MI. In some embodiments, the subject has undergone ischemicconditioning prior to the MI. In some embodiments, the ischemicconditioning prior to the MI was local or remote. In some embodiments,the ischemic conditioning during the MI was local or remote. It is to beunderstood that as used herein ischemic conditioning is a deliberateregimen performed on a subject and it does not embrace the ischemic andreperfusion phases that “naturally” occur during an MI.

In some embodiments, the method does not impact (e.g., reduce) the sizeof the infarct that results from the MI (i.e., the infarct size remainsrelatively unchanged by the method).

In some embodiments, the first RIC regimen is performed during ischemiaassociated with MI. In some embodiments, the first remote ischemicconditioning regimen is performed during reperfusion following ischemiaassociated with MI. In some embodiments, the first RIC regimen isperformed during the ischemia associated with MI only, or during theischemia performed during the ischemia associated with MI and then everyday thereafter, every two days thereafter, every three days thereafter,every four days thereafter, every five days thereafter, every six daysthereafter, or every seven days thereafter.

In some embodiments, the subsequent RIC regimens are performed everythree days, every two days, or every day after the first RIC regimen orafter the MI.

In some embodiments, the subsequent RIC regimens are performed for oneor more months after the MI. In some embodiments, the repeated RICregimens comprise more than one (e.g., 2, 3, 4, 5 or more) RIC regimensper day on one or more days.

In preferred embodiments, the subject is human. In some embodiments, thesubject is not at risk of restenosis, as described in greater detailherein. In some embodiments, the subject does not have a chronic medicalcondition such as hypertension.

The number of cycles per RIC regimen may be two, three, four, five, sixor more cycles, with each cycle comprising supra-systolic pressure andreperfusion. In some embodiments, at least one RIC regimen of therepeated RIC regimen comprises at least four cycles. In someembodiments, at least one RIC regimen of the repeated RIC regimencomprises more than one cycle comprising 5 minutes of supra-systolicpressure and 5 minutes of reperfusion. In some embodiments, thesupra-systolic pressure is a pressure that is at least an absolutenumber of mmHg above systolic pressure, or it is a percentage above ofsystolic pressure. The supra-systolic pressure may be a pressure that is5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or more mmHg above systolicpressure. In some embodiments, the supra-systolic pressure is a pressurethat is at least 15 mmHg above systolic pressure, and may range to 20,25, 30,35, 40, 45, 50 or more mmHg above systolic pressure. In someembodiments, the supra-systolic pressure is a pressure that is 1%, 2%,3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or more than systolic pressure. It is tobe understood that these percentages reflect a percentage of thesystolic pressure, such that the supra-systolic pressure may also bereferred to as being at a level that is 101%, 102%, 103%, 104%, 105%,106%, 107%, 108%, 109%, 110% (or more) of systolic pressure. In someembodiments, the supra-systolic pressure is at or about an absolutepressure such as for example at or about 170, 180, 190, 200, 210, 220,230 or more mmHg. In some embodiments, the supra-systolic pressure is apressure that is at or about 200 mmHg.

In some embodiments, each of the RIC regimens in the repeated RICregimen is performed at the same site. In some embodiments, the repeatedRIC regimen is performed on an upper limb. In one embodiment, anindividual RIC regimen or a repeated RIC regimen is performed using twoor more devices such as two or more cuffs, positioned at different siteson the body (e.g., one cuff per arm, or one cuff per leg, or one cuff onan arm and one cuff on a leg, etc.).

In some embodiments of the foregoing aspects, the subject is furthertreated using a defibrillator. The defibrillator may be an automatedexternal defibrillator (AED).

In some embodiments, the method further comprises administering to thesubject an angiotensin-converting enzyme (ACE) inhibitor. Examples ofACE inhibitors suitable to the invention include but are not limited tocaptopril, enalapril, ramipril, lisinopril, quinapril, fosinopril,benazepril, and moexipril.

In some embodiments, the method further comprises administering to thesubject an angiotensin II receptor blocker. Examples include but are notlimited to candesartan, irbesartin, losartin, telmisartin, andvalsartan.

In some embodiments, the method further comprises administering to thesubject an anti-platelet agent. Examples include aspirin andclopidogrel.

In some embodiments, the method further comprises administering to thesubject a statin.

In various embodiments, the subject may be administered two or more ofthese aforementioned agents.

In another aspect, the invention provides a kit comprising adefibrillator and a device for performing remote ischemic conditioning,such as for example the automated device described herein. Thedefibrillator may be an automated external defibrillator (AED).

These and other aspects and embodiments of the invention will bediscussed in greater detail herein.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures are not intended to be drawn to scale. In thefigures, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in every figure.

Various embodiments of the invention will now be described, by way ofexample, with reference to the accompanying figures, in which:

FIG. 1 is a schematic figure illustrating the experimental protocol.Rats were randomly assigned to different groups: 1) Sham group, whererats underwent sham operation without any intervention; 2) MI group,rats underwent 45 minutes ischemia followed by reperfusion with noconditioning therapy given; 3) sPost group, a single conditioning eventwas delivered before the end of ischemia and continued during theinitial reperfusion period; 4) dPost group, a single conditioning eventwas delivered on day 4 (72 hours after reperfusion); 5) rPost group,conditioning was given as in group 3 and then given every three daysuntil day 28 and 6) iPost group, conditioning was given as in group 3and then given every day until day 28. Vertical arrows indicate thedates (day 4 and day 28, respectively) for euthanization. All theabbreviations are the same as in the text.

FIG. 2. Panel A: Representative photomicrographs from each group ofrats, showing numbers of macrophages (upper panels) and neutrophils(lower panels) infiltrating the infarction zone of the heart on day 4after MI (magnification ×400, scale bar=50 μm). Panel B: Quantitativeanalysis of the number of infiltrating macrophages (positive ED-1staining) and neutrophils (positive MPO staining) in infarcted area.Panel C: Representative heart tissue slices of MCP-1 staining (shown inbrown) in border zone area from each group rats (magnification ×400,scale bar=50 μm). Data are expressed as mean±SD, with the sameabbreviations as above.

FIG. 3. Panel A: Photomicrographs of left ventricular tissue sectionswith immunostaining targeting 8-hydroxydeoxygaunosine (8-OHdG, shown inbrown staining) selected from each group of rats on day 28(magnification ×400, scale bar=50 μm). Panel B: Quantification ofmyocardial MDA concentrations in each group on day 28. Panel C:Quantitative analysis of plasma TNF-α (Panel A) and IL-1β (Panel B)levels in each group rats on day 28 after MI. Data are expressed asmean±SD, with the same abbreviations as above.

FIG. 4. Panel A: Representative western blot bands showingphospho-IκB_(α,) IκB_(α) and GAPDH (on the left side) and phospho-NFκBP65, NFκB P65 and GAPDH (on the right side) from each group rats. PanelB: Quantification of ratio of phospho-IκB_(α) over IκB_(α) proteinexpression and phospho-NFκB P65 over NFκB P65 protein expression wereshown in bar graphs (GAPDH as loading control). Data are expressed asmean±SD, with the same abbreviations as above.

FIG. 5 shows representative Western blot bands for phospho-Smad2 andSmad2, ratio of phosphor Smad2 over total Smad2 protein expression wasshown in bar graph (Panel A). TGF-β1 from each group of rats was alsoshown in Panel B. GAPDH was for protein loading control. Data areexpressed as mean±SD, with the same abbreviations as above.

FIG. 6. Panel A: Representative sections with Masson's trichromestaining (stained in blue, magnification ×400, scale bar=50 μm) withinborder zone area of each group of rat hearts. Panel B: Quantitativeanalyses of extent of interstitial fibrosis for each group. Data areexpressed as mean±SD, with the same abbreviations as above.

FIG. 7. Panel A: Representative photomicrographs to show variations ofcross section area of cardiomyocytes stained with hematoxylin and eosin(magnification ×400). Panel B: Quantitative morphometric analysis ofcardiomyocyte cross sectional area (mm²) Panel C, D and E showed themRNA expression of α-MHC, β-MHC and ANP. Data are expressed as mean±SD,with the same abbreviations as above.

FIG. 8 is a schematic representation of one embodiment of a remoteischemic conditioning system, including a pneumatically inflatable cuffconfigured to contract about the limb of a subject.

FIG. 9 is a block diagram of one embodiment of an operating scheme ofthe RIC system.

FIG. 10 shows an alternate embodiment of a cuff configured to contractabout the limb of a subject.

FIG. 11. A. Schematic for treatment groups. B. Kaplan Meier curves(survival rates) over an 85 day period following an MI are shown for asham group, an MI group that received no treatment, an rIPerC group thatreceived RIC during the ischemic phase of the MI, an rPostC group thatreceived RIC during the ischemic phase of the MI and every three daysthereafter, an iPostC group that received RIC during the ischemic phaseof the MI and every day thereafter, and an SP group that received sodiumpentobarbital to control for the effects of the repeated anaesthesia. *denotes P<0.05 vs. MI group; ^(#), P<0.001 vs. MI group, ^(&), P<0.05vs. rIPerC group.

Table 1 presents data obtained from each group of rats to assess cardiacgeometry, function, infarct size and hemodynamic changes.

DETAILED DESCRIPTION OF THE INVENTION

The invention is premised, in part, on the finding that heartdysfunction/failure post-MI can be reduced, delayed or preventedaltogether by deliberately and, in some instances, repeatedly performingcycles of induced transient ischemia and reperfusion in subjects duringand/or after an MI. The invention is also premised in part on thefinding that performing induced transient ischemia and reperfusion onsubjects during an MI, including during the ischemia associated with anMI has similar benefits. The use of induced transient ischemia andreperfusion according to the invention is also associated with increasedsurvival in subjects post-MI.

The invention provides methods for reducing the risk, delaying theonset, and/or reducing the severity of heart dysfunction/failurefollowing MI. The invention aims to ameliorate or prevent heartdysfunction/failure that occurs as a result of MI. The invention does soby subjecting the subject having or who has had an MI to one or more RICregimens. In some aspects of the invention, at least one of theseregimens (including the only one that the subject may receive) isperformed during the MI. These are referred to as “per-conditioning”regimens, and they can occur during the ischemic phase of an MI and/orthe reperfusion phase that follows. In certain embodiments, subjectsreceive an RIC regimen during the MI, including during the ischemicphase of the MI. In these and other aspects of the invention, one ormore regimens may be performed following the MI. These are referred toas “post-conditioning” regimens. Thus, some methods of the inventioninvolve performing RIC on a subject while such subject is experiencingan MI, and optionally after the MI. Other methods of the inventioninvolve performing RIC on a subject following an MI, optionally if anRIC regimen has been performed on the subject during the prior MI. Insome embodiments, RIC may be performed during an MI (e.g., during theischemic phase of an MI, during the reperfusion phase of an MI, orduring the ischemic and reperfusion phases of the MI), and/orimmediately after the cessation of an MI (e.g., within hours, andpreferably within an hour), and/or following the MI (as discussedbelow). In some embodiments, the subject has not received anypre-conditioning RIC regimens (i.e., an RIC regimen before the MI). Insome embodiments, the subject has received one or more pre-conditioningRIC regimens.

Thus, in some aspects, the methods involve performing RIC during the MIand repeatedly after the MI. In some aspects, the methods involveperforming RIC repeatedly after an MI even if RIC was not performedduring the MI. Such RIC may be referred to herein as post-MI RIC. Insome embodiments, post-MI RIC is performed days, weeks, or months afteran MI. Thus the time in between the MI and the first RIC may be 1, 2, 3,4, 5, or 6 days, or 1, 2, 3, or 4 weeks, or 1, 2, 3, 4, 5, 6, or moremonths, or longer.

In some embodiments, heart function is improved and/or heartdysfunction/failure is reduced, as described above, even if the infarctitself is not affected by the RIC that occurs post-MI. That is, theinfarct size does not appear to be impacted by the post-MI RIC relativeto the effect of a single RIC at the time of the MI. In someembodiments, survival time is increased.

It has been found quite surprisingly, according to the invention, thatsubjecting an individual to RIC during and after MI protects the subjectagainst adverse remodeling that otherwise occurs following ischemic andreperfusion heart injury, such as most typically occurs with an MI. Evenmore surprisingly, this benefit is achieved even if there is no effecton infarct size. That is, the long term remodeling effects do not appearto be associated with any change (e.g., reduction) in infarct sizeresulting from the MI.

It is also surprising that the post-conditioning regimens have beenfound to provide therapeutic benefit particularly since it had beenthought heretofore that ischemic conditioning had to be performed priorto an ischemic event (i.e., “pre-conditioning”). The invention evidencesthat, regardless of whether a subject has undergone any form of ischemicpre-conditioning, it can still benefit from ischemic post-conditioningat least to the extent that such post-conditioning reduces or preventsheart dysfunction/failure associated with MI.

As described in the Examples, therapeutic post-MI benefit can beachieved by performing a single RIC regimen on a subject during an MI.This regimen may occur during the ischemic phase of an MI and/or duringthe reperfusion phase of an MI. Thus, the invention contemplates, insome instances, that once a subject is identified as one having an MI,as known in the art and as described below, then someone attending tothat subject, including but not limited to medically trained personnel,will perform an RIC regimen on that subject. This regimen, as describedin greater detail below, involves performing one and preferably morethan one ischemia-reperfusion cycle to a remote location on the subject.Such locations are preferably easily accessible and the regimen ispreferably a non-invasive regimen. Typically, the regimen is performedon one or more limbs through application of pressure at the skin (forexample, through the use of a pressure cuff or a tourniquet).

In the experimental model used in the Examples, a single conditioningregimen during the reperfusion phase of an MI provided long-term benefitwhile a single conditioning regimen performed at day 4 (with the MIbeginning on day 1) had no effect.

Thus, in some embodiments of the invention, an RIC regimen is performedwithin 30 days, or within 20 days, 10 days or within one 1 day, orwithin 12 hours, or within 6 hours, or within 3 hours, or within 2hours, within 1 hour, within 30 minutes, within 10 minutes, or within 5minutes of the myocardial infarction, and/or at the time of themyocardial infarction.

The Examples further show, again surprisingly, that even more benefitcan be obtained when multiple RIC regimens are performed on the subjectpost-MI. More specifically, more protection against the adverse effectsof remodeling and increased survival time were observed when multipleRIC regimens were performed following the MI. It was found thatperforming RIC once every three days after the MI provided greaterprotection than a single regimen at the time of the MI Importantly,infarct size was not significantly different between the two groups ofanimals, indicating that the beneficial effects provided by this earlyconditioning regimen were independent of effect on the infarct.

It was further found that performing RIC daily after the MI providedeven greater protection and higher rates of survival than when it wasperformed once every three days.

Accordingly, the invention in some instances provides methods thatinvolve performing RIC on a subject at least once a week, at least onceevery 6 days, at least once every 5 days, or at least once every 4 daysfollowing an MI, preferably where RIC has also been performed during theMI. In some important embodiments, the remote ischemic conditioning isperformed on a subject at least once every 3 days, at least once every 2days, or at least once every day (i.e., daily) following an MI,preferably where RIC has also been performed during the MI.

As used herein, “at least once” as in for example “at least once everythree days” means that in a three day period at least one RIC regimen isperformed. As a result, this includes instances in which the RIC isperformed every day, every two days, or every three days. Alternativelyor additionally it includes instances in which on the first, second,and/or third day of the three day period, one or more RIC regimens areperformed. In the simplest case, one RIC is performed every three days.However, it is to be understood that the invention contemplates morefrequent performance on any given day. It is also to be understood thatthis same meaning applies for regimens that are performed at otherfrequencies, as recited above. Thus, for the sake of clarity, “at leastdaily” means that every day one or more RIC regimens is performed.

In some embodiments, a single RIC regimen is performed on a single day.In other embodiments, more than one, including 2, 3, 4, 5 or more, RICregimens are performed on a single day.

Whether performed on a single day or on different days, the RIC regimenmay be performed at the same location or at different locations. Thesemay alternate between two locations or they may cycle through more thantwo locations. The use of more than one location may be determined apriori or it may be random. In some embodiments, a single regimen may beperformed using a single location or multiple locations. For example, asingle regimen may be performed at a single location on an upper arm ofa human subject or it may be performed using two upper arm locations(e.g., separate upper arms) simultaneously or in an alternating manner.When multiple locations are used, two or more devices may be used.

The foregoing regimens are considered to be regular in nature to theextent that the frequency of the regimens is determined a priori andcarried out in like manner. It will be clear that the time in betweenregimens may be uniform (or identical) or it may differ, provided thatsuch timing is known ahead of time. The invention contemplates protocolsin which at least two sets of two contiguous regimens are separated by afirst time period and at least two other sets of two contiguous regimensare separated by a second time period that is different from the firsttime period.

The invention however contemplates the performance of randomly spacedmultiple regimens post-MI, provided however that even in such instancesthe regimens are performed at least as frequently as once every week.

The remote ischemic conditioning regimens may be performed over any timeperiod including without limitation for up to 1 month, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, or 12 months, or longer following an MI. In someinstances, the regimens occur over years including up to 2, 3, 4, 5, ormore years. In still other instances, the regimens continue over theremaining lifespan of the subject or until it is determined that thesubject is no longer at an elevated risk of heart dysfunction/failure.As used herein, an elevated risk of heart dysfunction/failure is a riskthat is higher than the risk of the average population that has notexperienced an MI. Thus, although the Examples show the effects of RICregimens that are performed up to 30 days post-experimentally simulatedMI, the invention contemplates both shorter and longer “treatment”times.

The subjects to be “treated” by the invention minimally are experiencingor have experienced an MI. They may or may not have been subjected toischemic pre-conditioning (i.e., ischemic conditioning prior to the MI).They may or may not have a condition for which ischemic conditioning,including ischemic pre-conditioning, is indicated. They may or may notbe at risk of restenosis, for example following a medical procedure orintervention that involves widening or dilation of a blood or othervessel in the body. Examples of such medical procedures or interventionsinclude but are not limited to angioplasty or stent placement.Similarly, the subject may or may not be one who has undergone a medicalintervention that induced or is likely to induce vessel damage. Thesubject may or may not present with or have a history of a chronicmedical condition such as but not limited to hypertension. The subjectsof the invention will preferably be humans, although non-human subjectsare also contemplated.

As used herein, the term “treat” means to have a positive or therapeuticbenefit on the likelihood, onset time, and/or severity of heartdysfunction/failure the subject may experience post-MI. Such positive ortherapeutically beneficial effects may be measured by comparing thesubject to a population that has not been subjected to the methods ofthe invention. The subject and the population can be compared in termsof incidence of heart dysfunction/failure, time of onset of heartdysfunction/failure, and severity of heart dysfunction/failure. Heartdysfunction/failure indicia are described in greater detail below.

Based on the foregoing, therefore, it should be clear that the inventioncontemplates performing RIC regimens on subjects who are having an MI aswell as those who have already had an MI particularly if these lattersubjects were administered an ischemic conditioning regimen at or nearthe time of the MI, whether locally or remotely.

Those of ordinary skill in the art, including but not limited to medicalpractitioners and medical emergency personnel, will be familiar with thecharacteristics of an MI. Symptoms of MI, particularly in men, includesudden chest pain (often times radiating to the left arm or left side ofneck), shortness of breath, nausea, vomiting, palpitations, sweating,and anxiety. Symptoms in women differ somewhat from those in men, andtypically include shortness of breath, weakness, indigestion, andfatigue. Whether in the presence or absence of such symptoms, MI may bedetected using, for example, electrocardiograms, blood marker tests(e.g., creatine-kinase, troponin T or I), and heart imaging such aschest X-rays. Guidelines for diagnosing an MI include the WIIO criteria(i.e., history of ischemic type chest pain lasting for more than 20minutes, changes in serial ECG tracings, and rise/fall of serum cardiacmarkers such as creatine kinase MB and troponin) in which the presenceof two and three such criteria indicate probable and definite MI,respectively.

As used herein, the term “remote ischemic conditioning regimen” or “RICregimen” refers to one or more ischemia-reperfusion cycles performed ona subject at a location on the body other than the heart (i.e., a“remote” location). As used herein, an RIC regimen (or an individual RICregimen) means at least one cycle of an induced transient ischemic eventfollowed by a reperfusion event. An individual RIC regimen therefore maybe comprised of 1, 2, 3, 4, 5, or more such cycles.

The invention contemplates, in some aspects, performing a repeated RICregimen on a subject. As used herein, a repeated RIC regimen is two ormore individual RIC regimens that occur on a single day and/or one ormore RIC regimens that occur on a number of days. For example, therepeated RIC regimen may comprise performing multiple RIC regimens on asingle day, or performing single RIC regimens on a number of days, orperforming multiple RIC regimens on a number of days. If the repeatedRIC regimen occurs on a single day, the time between individual regimensmay be at least 10 minutes, at least 20 minutes, at least 40 minutes, atleast 1 hour, at least 2 hours, or at least 6 hours, for example. If therepeated RIC regimen occurs over the course of several days, the timebetween individual regimens may be 1 day, 2 days, 3 days, 4 days, 5days, 6 days or 7 days. The totality of the repeated RIC regimens isreferred to herein as an RIC protocol.

As discussed herein, there is no requirement that any or all of the RICregimens in a repeated RIC regimen be identical with respect to timing,number of cycles per regimen, supra-systolic pressure, location, and thelike.

Typically, RIC is performed on a limb such as an upper or lower limb,although it is not so limited. The repeated RIC regimen may be performedon a single site or on multiple sites in the body. For example, therepeated RIC regimen may comprise a first RIC regimen performed on theright upper arm, followed by a second RIC regimen performed on the leftupper arm. The repeated RIC regimen may comprise alternation betweenremote sites on the body. In some instances, an RIC regimen may beperformed on a subject at two different sites at overlapping timesincluding simultaneously. In such instances, two devices may be used, asdescribed below.

Heart Dysfunction/Failure

Heart failure is defined as the inability of the heart to pump bloodthrough the body or to prevent blood from backing up into the lungs.Heart failure is often times referred to as congestive heart failure andis associated with systolic or diastolic heart dysfunction. It typicallydevelops over time and may be triggered or exacerbated by anothercondition that causes heart tissue damage (e.g., an MI) or that causesthe heart tissue to work more (or harder) than normal.

Accordingly, and as will be understood by those of ordinary skill in theart, heart failure indicates heart dysfunction and the inventioncontemplates reducing the risk, delaying the onset, preventing and/ortreating heart dysfunction in the presence or absence of heart failure.The discussion of heart failure herein is therefore intended to captureheart dysfunction also, unless stated otherwise.

The invention provides, in some instances, methods for reducing the riskof heart dysfunction/failure in subjects who have had or are having anMI. The method is intended to reduce the development and/or severity ofheart dysfunction/failure and its associated symptoms which include butare not limited to, exercise intolerance, arrhythmia and sudden death,as a result of the MI. Development and severity of heartdysfunction/failure can be measured by monitoring and measuring symptomsor other characteristics associated with heart dysfunction/failure.These are discussed below. The methods may lead to the prevention of allor some such symptoms, the delayed onset of all or some such symptoms,and/or the reduction in the severity of all or some such symptoms. Areduction in the risk of heart dysfunction/failure may be determined bymonitoring the symptoms or other characteristics associated with heartdysfunction/failure in the treated subject and comparing the number,onset, and severity of such symptoms or characteristics in that subjectwith historical population data for heart dysfunction/failure. Forexample, it is known that subjects that survive MI are more likely todevelop heart dysfunction/failure than the average population. Themethods of the invention aim to reduce this likelihood or risk of heartdysfunction/failure development.

Symptoms of heart dysfunction/failure include shortness of breath(dyspnea), swelling in the feet and legs (edema) typically as a resultof abnormal fluid retention, fluid in the lungs, persistent coughing orwheezing, low exercise tolerance, general fatigue even in the absence ofexercise, increased heart rate (or palpitations), loss of appetite,memory loss (or confusion), and nausea. One and typically more than oneof these symptoms will be manifest in subjects having heartdysfunction/failure. The methods of the invention aim to prevent thedevelopment, delay the onset, and/or reduce the severity of one or moreof these symptoms.

Heart dysfunction/failure can be diagnosed based on presentation of oneand typically more than one of the foregoing symptoms. Heartdysfunction/failure can also be diagnosed or a suspected diagnosis ofheart dysfunction/failure can be confirmed with tests such as anelectrocardiogram (ECG or EKG), an echocardiogram (“cardiac echo”), orcardiac catheterization. Echocardiograms, for example, are able tomeasure the volume or fraction of blood that is ejected from the leftventricle with each beat. This is referred to as the ejection fraction.In normal subjects, about 60% of the blood in the left ventricle isejected. Subjects may present with mildly depressed ejection fractions(e.g., 40-45%), moderately depressed ejection fractions (e.g., 30-40%),or severely depressed ejection fractions (e.g., 10-25%). Thus, in someaspects of the invention, the methods aim to maintain the ejectionfraction, particularly if the subject presents with normal or mildlydepressed ejection fractions. In some aspects, the methods of theinvention aim to delay the onset of a depressed ejection fraction,regardless of the initial ejection fraction presentation. Stress testsmay also be used to diagnose heart dysfunction/failure, and they may becombined with one or more of the imaging tests discussed above. Forexample, a stress test may be combined with an echocardiogram in orderto monitor and measure heart dysfunction/failure before, during and/orfollowing exercise periods. Those of ordinary skill in the art,including medical practitioners and more particularly cardiologists,will be familiar these tests and their use in diagnosing heartdysfunction/failure.

It will be understood that the subjects intended to be treated accordingto the methods of the invention will also have a history of or evidencefor, one or more MI. In some aspects, the subject may or may not presentor have a history of other risk factors or other conditions. Forexample, in one embodiment, the subjects may not have a history and/ormay not present with high blood pressure (hypertension). As anotherexample, in one embodiment, the subjects may not have undergone amedical procedure or intervention that aims to dilate a tube such as anartery or vein in the subject. Examples of such interventions includeangioplasty, stent placement, and the like.

Importantly, in some instances, one or more of the benefits provided bythe methods of the invention occur independently of any effect on themyocardial infarct size or volume. That is, as described in theExamples, in some embodiments provided a first cycle of RIC is appliedduring an MI or shortly thereafter, the infarct size may not besignificantly reduced through subsequent chronic RIC. However,surprisingly, even in the absence of any further reduction in theinfarct size, it is still possible to reduce the risk, onset and/orseverity of heart dysfunction/failure using the methods of theinvention. Although not intending to be limited to any particularmechanism of action to explain this finding, chronic RIC may prevent orrestrict the degree of left ventricular remodeling that occurspost-myocardial infarction. As discussed in the Examples, repeatedpost-MI RIC regimens may attenuate inflammatory responses, reduceoxidative stress, and/or modulate hypertrophic and fibrotic signalsassociated with MI.

Some methods of the invention therefore comprise performing an RICregimen on a subject during and/or after (including shortly after) amyocardial infarction. Preferably, one RIC regimen is performed on thesubject during the myocardial infarction. In these embodiments, it maybe performed during the ischemic phase (or period), or during thereperfusion phase (or period), or it may overlap both phases to varyingdegrees. If performed during the myocardial infarction, the conditioningis referred to herein as perconditioning. In other embodiments, the RICregimen is performed within 30 minutes, within 1 hour, 2 hours, 3 hours,4 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 18 hours, or 24hours of the end of the ischemic period of the myocardial infarction. Instill other embodiments, the RIC regimen is performed within 36 hours,48 hours, or 60 hours of the myocardial infarction.

Subsequent RIC regimens may be performed on a daily basis, every otherday, or every three days. These RIC regimens may be performed once aday, or more than once a day, including twice a day, 3 times a day, ormore.

Additional Therapies

The RIC regimens of the invention may be used in combination with othertherapies or procedures aimed at reducing the risk or severity of heartdysfunction/failure. These therapies include without limitationantiplatelet drug therapy including fibrinolytic agents,anti-coagulation agents, and platelet function inhibitors, beta blockertherapy, ACE inhibitor therapy, statin therapy, aldosterone antagonisttherapy (e.g., eplerenone), and omega-3-fatty acids therapy. Dependingupon the embodiment, one or more of these agents may be administeredbefore, at the time of, or after MI, whether or not overlapping with theRIC regimens and/or protocol. These and other suitable therapies arediscussed in greater detail below.

Fibrinolytic agents are agents that lyse a thrombus (e.g., a bloodclot), usually through the dissolution of fibrin by enzymatic action.Examples include but are not limited to ancrod, anistreplase, bisobrinlactate, brinolase, Hageman factor (i.e. factor XII) fragments,molsidomine, plasminogen activators such as streptokinase, tissueplasminogen activators (TPA) and urokinase, and plasmin and plasminogen.

Anti-coagulant agents are agents that inhibit the coagulation pathway byimpacting negatively upon the production, deposition, cleavage and/oractivation of factors essential in the formation of a blood clot.Anti-coagulant agents include but are not limited to vitamin Kantagonists such as coumarin and coumarin derivatives (e.g., warfarinsodium); glycosoaminoglycans such as heparins both in unfractionatedform and in low molecular weight form; ardeparin sodium, bivalirudin,bromindione, coumarin dalteparin sodium, desirudin, dicumarol, lyapolatesodium, nafamostat mesylate, phenprocoumon, sulfatide, tinzaparinsodium, inhibitors of factor Xa, factor TFPI, factor VIIa, factor IXc,factor Va, factor VIIIa as well as inhibitors of other coagulationfactors.

Inhibitors of platelet function are agents that impair the ability ofmature platelets to perform their normal physiological roles (i.e.,their normal function). Examples include but are not limited toacadesine, anagrelide, anipamil, argatroban, aspirin, clopidogrel,cyclooxygenase inhibitors such as nonsteroidal anti-inflammatory drugsand the synthetic compound FR-122047, danaparoid sodium, dazoxibenhydrochloride, diadenosine 5′,5′″-P1,P4-tetraphosphate (Ap4A) analogs,difibrotide, dilazep dihydrochloride, 1,2- and 1,3-glyceryl dinitrate,dipyridamole, dopamine and 3-methoxytyramine, efegatran sulfate,enoxaparin sodium, glucagon, glycoprotein IIb/IIIa antagonists such asRo-43-8857 and L-700,462, ifetroban, ifetroban sodium, iloprost,isocarbacyclin methyl ester, isosorbide-5-mononitrate, itazigrel,ketanserin and BM-13.177, lamifiban, lifarizine, molsidomine,nifedipine, oxagrelate, PGE, platelet activating factor antagonists suchas lexipafant, prostacyclin (PGI₂), pyrazines, pyridinol carbamate,ReoPro (i.e., abciximab), sulfinpyrazone, synthetic compounds BN-50727,BN-52021, CV-4151, E-5510, FK-409, GU-7, KB-2796, KBT-3022, KC-404,KF-4939, OP-41483, TRK-100, TA-3090, TFC-612 and ZK-36374,2,4,5,7-tetrathiaoctane, 2,4,5,7-tetrathiaoctane 2,2-dioxide,2,4,5-trithiahexane, theophyllin pentoxifyllin, thromboxane andthromboxane synthetase inhibitors such as picotamide and sulotroban,ticlopidine, tirofiban, trapidil and ticlopidine, trifenagrel,trilinolein, 3-substituted 5,6-bis(4-methoxyphenyl)-1,2,4-triazines, andantibodies to glycoprotein IIb/IIIa as well as those disclosed in U.S.Pat. No. 5,440,020, and anti-serotonin drugs, Clopridogrel;Sulfinpyrazone; Aspirin; Dipyridamole; Clofibrate; Pyridinol Carbamate;PGE; Glucagon; Antiserotonin drugs; Caffeine; Theophyllin Pentoxifyllin;Ticlopidine.

Anti-inflammatory agents include Alclofenac; Alclometasone Dipropionate;Algestone Acetonide; Alpha Amylase; Amcinafal; Amcinafide; AmfenacSodium; Amiprilose Hydrochloride; Anakinra; Anirolac; Anitrazafen;Apazone; Balsalazide Disodium; Bendazac; Benoxaprofen; BenzydamineHydrochloride; Bromelains; Broperamole; Budesonide; Carprofen;Cicloprofen; Cintazone; Cliprofen; Clobetasol Propionate; ClobetasoneButyrate; Clopirac; Cloticasone Propionate; Cormethasone Acetate;Cortodoxone; Deflazacort; Desonide; Desoximetasone; DexamethasoneDipropionate; Diclofenac Potassium; Diclofenac Sodium; DiflorasoneDiacetate; Diflumidone Sodium; Diflunisal; Difluprednate; Diftalone;Dimethyl Sulfoxide; Drocinonide; Endrysone; Enlimomab; Enolicam Sodium;Epirizole; Etodolac; Etofenamate; Felbinac; Fenamole; Fenbufen;Fenclofenac; Fenclorac; Fendosal; Fenpipalone; Fentiazac; Flazalone;Fluazacort; Flufenamic Acid; Flumizole; Flunisolide Acetate; Flunixin;Flunixin Meglumine; Fluocortin Butyl; Fluorometholone Acetate;Fluquazone; Flurbiprofen; Fluretofen; Fluticasone Propionate;Furaprofen; Furobufen; Halcinonide; Halobetasol Propionate; HalopredoneAcetate; Ibufenac; Ibuprofen; Ibuprofen Aluminum; Ibuprofen Piconol;Ilonidap; Indomethacin; Indomethacin Sodium; Indoprofen; Indoxole;Intrazole; Isoflupredone Acetate; Isoxepac; Isoxicam; Ketoprofen;Lofemizole Hydrochloride; Lornoxicam; Loteprednol Etabonate;Meclofenamate Sodium; Meclofenamic Acid; Meclorisone Dibutyrate;Mefenamic Acid; Mesalamine; Meseclazone; Methylprednisolone Suleptanate;Morniflumate; Nabumetone; Naproxen; Naproxen Sodium; Naproxol; Nimazone;Olsalazine Sodium; Orgotein; Orpanoxin; Oxaprozin; Oxyphenbutazone;Paranyline Hydrochloride; Pentosan Polysulfate Sodium; PhenbutazoneSodium Glycerate; Pirfenidone; Piroxicam; Piroxicam Cinnamate; PiroxicamOlamine; Pirprofen; Prednazate; Prifelone; Prodolic Acid; Proquazone;Proxazole; Proxazole Citrate; Rimexolone; Romazarit; Salcolex;Salnacedin; Salsalate; Salycilates; Sanguinarium Chloride; Seclazone;Sermetacin; Sudoxicam; Sulindac; Suprofen; Talmetacin; Talniflumate;Talosalate; Tebufelone; Tenidap; Tenidap Sodium; Tenoxicam; Tesicam;Tesimide; Tetrydamine; Tiopinac; Tixocortol Pivalate; Tolmetin; TolmetinSodium; Triclonide; Triflumidate; Zidometacin; Glucocorticoids;Zomepirac Sodium. One preferred anti-inflammatory agent is aspirin.

Lipid reducing agents include gemfibrozil, cholystyramine, colestipol,nicotinic acid, probucol lovastatin, and statins such as fluvastatin,simvastatin, atorvastatin, pravastatin, and cirivastatin.

Direct thrombin inhibitors include hirudin, hirugen, hirulog, agatroban,PPACK, thrombin aptamers.

Glycoprotein IIb/IIIa receptor inhibitors are both antibodies andnon-antibodies, and include but are not limited to ReoPro (abcixamab),lamifiban, tirofiban.

Calcium channel blockers are a chemically diverse class of compoundshaving important therapeutic value in the control of a variety ofdiseases including several cardiovascular disorders, such ashypertension, angina, and cardiac arrhythmias (Fleckenstein, Cir. Res.v. 52, (suppl. 1), p. 13-16 (1983); Fleckenstein, Experimental Facts andTherapeutic Prospects, John Wiley, New York (1983); McCall, D., CurrPract Cardiol, v. 10, p. 1-11 (1985)). Calcium channel blockers are aheterogeneous group of drugs that prevent or slow the entry of calciuminto cells by regulating cellular calcium channels. (Remington, TheScience and Practice of Pharmacy, Nineteenth Edition, Mack PublishingCompany, Eaton, Pa., p. 963 (1995)). Most of the currently availablecalcium channel blockers, and useful according to the present invention,belong to one of three major chemical groups of drugs, thedihydropyridines, such as nifedipine, the phenyl alkyl amines, such asverapamil, and the benzothiazepines, such as diltiazem. Other calciumchannel blockers useful according to the invention, include, but are notlimited to, amrinone, amlodipine, bencyclane, felodipine, fendiline,flunarizine, isradipine, nicardipine, nimodipine, perhexilene,gallopamil, tiapamil and tiapamil analogues (such as 1993RO-11-2933),phenytoin, barbiturates, and the peptides dynorphin, omega-conotoxin,and omega-agatoxin, and the like and/or pharmaceutically acceptablesalts thereof.

Beta-adrenergic receptor blocking agents (also known as beta blockers)are a class of drugs that antagonize the cardiovascular effects ofcatecholamines in angina pectoris, hypertension, and cardiacarrhythmias. Beta-adrenergic receptor blockers include, but are notlimited to, atenolol, acebutolol, alprenolol, befunolol, betaxolol,bunitrolol, carteolol, celiprolol, hedroxalol, indenolol, labetalol,levobunolol, mepindolol, methypranol, metindol, metoprolol,metrizoranolol, oxprenolol, pindolol, propranolol, practolol, practolol,sotalolnadolol, tiprenolol, tomalolol, timolol, bupranolol, penbutolol,trimepranol,2-(3-(1,1-dimethylethyl)-amino-2-hydroxypropoxy)-3-pyridenecarbonitrilHCl,1-butylamino-3-(2,5-dichlorophenoxy)-2-propanol,1-isopropylamino-3-(4-(2-cyclopropylmethoxyethyl)phenoxy)-2-propanol,3-isopropylamino-1-(7-methylindan-4-yloxy)-2-butanol,2-(3-t-butylamino-2-hydroxy-propylthio)-4-(5-carbamoyl-2-thienyl)thiazol,7-(2-hydroxy-3-t-butylaminpropoxy)phthalide. The above-identifiedcompounds can be used as isomeric mixtures, or in their respectivelevorotating or dextrorotating form.

A number of selective “COX-2 inhibitors” are known in the art. Theseinclude, but are not limited to, COX-2 inhibitors described in U.S. Pat.No. 5,474,995 “Phenyl heterocycles as cox-2 inhibitors”; U.S. Pat. No.5,521,213 “Diaryl bicyclic heterocycles as inhibitors ofcyclooxygenase-2”; U.S. Pat. No. 5,536,752 “Phenyl heterocycles as COX-2inhibitors”; U.S. Pat. No. 5,550,142 “Phenyl heterocycles as COX-2inhibitors”; U.S. Pat. No. 5,552,422 “Aryl substituted 5,5 fusedaromatic nitrogen compounds as anti-inflammatory agents”; U.S. Pat. No.5,604,253 “N-benzylindol-3-yl propanoic acid derivatives ascyclooxygenase inhibitors”; U.S. Pat. No. 5,604,260“5-methanesulfonamido-1-indanones as an inhibitor of cyclooxygenase-2”;U.S. Pat. No. 5,639,780 N-benzyl indol-3-yl butanoic acid derivatives ascyclooxygenase inhibitors“; U.S. Pat. No. 5,677,318Diphenyl-1,2-3-thiadiazoles as anti-inflammatory agents”; U.S. Pat. No.5,691,374 “Diaryl-5-oxygenated-2-(5H)-furanones as COX-2 inhibitors”;U.S. Pat. No. 5,698,584 “3,4-diaryl-2-hydroxy-2,5-dihydrofurans asprodrugs to COX-2 inhibitors”; U.S. Pat. No. 5,710,140 “Phenylheterocycles as COX-2 inhibitors”; U.S. Pat. No. 5,733,909 “Diphenylstilbenes as prodrugs to COX-2 inhibitors”; U.S. Pat. No. 5,789,413“Alkylated styrenes as prodrugs to COX-2 inhibitors”; U.S. Pat. No.5,817,700 “Bisaryl cyclobutenes derivatives as cyclooxygenaseinhibitors”; U.S. Pat. No. 5,849,943 “Stilbene derivatives useful ascyclooxygenase-2 inhibitors”; U.S. Pat. No. 5,861,419 “Substitutedpyridines as selective cyclooxygenase-2 inhibitors”; U.S. Pat. No.5,922,742 “Pyridinyl-2-cyclopenten-1-ones as selective cyclooxygenase-2inhibitors”; U.S. Pat. No. 5,925,631 “Alkylated styrenes as prodrugs toCOX-2 inhibitors”; all of which are commonly assigned to Merck FrosstCanada, Inc. (Kirkland, Calif.). Additional COX-2 inhibitors are alsodescribed in U.S. Pat. No. 5,643,933, assigned to G. D. Searle & Co.(Skokie, Ill.), entitled: “Substituted sulfonylphenylheterocycles ascyclooxygenase-2 and 5-lipoxygenase inhibitors.”

A number of the above-identified COX-2 inhibitors are prodrugs ofselective COX-2 inhibitors, and exert their action by conversion in vivoto the active and selective COX-2 inhibitors. The active and selectiveCOX-2 inhibitors formed from the above-identified COX-2 inhibitorprodrugs are described in detail in WO 95/00501, published Jan. 5, 1995,WO 95/18799, published Jul. 13, 1995 and U.S. Pat. No. 5,474,995, issuedDec. 12, 1995. Given the teachings of U.S. Pat. No. 5,543,297, entitled:“Human cyclooxygenase-2 cDNA and assays for evaluating cyclooxygenase-2activity,” a person of ordinary skill in the art would be able todetermine whether an agent is a selective COX-2 inhibitor or a precursorof a COX-2 inhibitor, and therefore part of the present invention.

An angiotensin system inhibitor is an agent that interferes with thefunction, synthesis or catabolism of angiotensin II. These agentsinclude, but are not limited to, angiotensin-converting enzyme (ACE)inhibitors, angiotensin II antagonists, angiotensin II receptorantagonists, agents that activate the catabolism of angiotensin II, andagents that prevent the synthesis of angiotensin I from whichangiotensin II is ultimately derived. The renin-angiotensin system isinvolved in the regulation of hemodynamics and water and electrolytebalance. Factors that lower blood volume, renal perfusion pressure, orthe concentration of Na⁺ in plasma tend to activate the system, whilefactors that increase these parameters tend to suppress its function.

Angiotensin II antagonists are compounds which interfere with theactivity of angiotensin II by binding to angiotensin II receptors andinterfering with its activity. Angiotensin II antagonists are well knownand include peptide compounds and non-peptide compounds. Mostangiotensin II antagonists are slightly modified congeners in whichagonist activity is attenuated by replacement of phenylalanine inposition 8 with some other amino acid; stability can be enhanced byother replacements that slow degeneration in vivo. Examples ofangiotensin II antagonists include but are not limited to peptidiccompounds (e.g., saralasin, [(San¹⁾(Val⁵)(Ala⁸)] angiotensin-(1-8)octapeptide and related analogs); N-substituted imidazole-2-one (U.S.Pat. No. 5,087,634); imidazole acetate derivatives including2-N-butyl-4-chloro-1-(2-chlorobenzile)imidazole-5-acetic acid (see Longet al., J. Pharmacol. Exp. Ther. 247(1), 1-7 (1988)); 4, 5, 6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid and analogderivatives (U.S. Pat. No. 4,816,463); N2-tetrazole beta-glucuronideanalogs (U.S. Pat. No. 5,085,992); substituted pyrroles, pyrazoles, andtryazoles (U.S. Pat. No. 5,081,127); phenol and heterocyclic derivativessuch as 1,3-imidazoles (U.S. Pat. No. 5,073,566); imidazo-fused 7-memberring heterocycles (U.S. Pat. No. 5,064,825); peptides (e.g., U.S. Pat.No. 4,772,684); antibodies to angiotensin II (e.g., U.S. Pat. No.4,302,386); and aralkyl imidazole compounds such as biphenyl-methylsubstituted imidazoles (e.g., EP Number 253,310, Jan. 20, 1988); ES8891(N-morpholinoacetyl-(-1-naphthyl)-L-alanyl-(4,thiazolyl)-L-alanyl(35,45)-4-amino-3-hydroxy-5-cyclo-hexapentanoyl-N-hexylamide,Sankyo Company, Ltd., Tokyo, Japan); SKF108566(E-alpha-2-[2-butyl-1-(carboxyphenyl)methyl]1H-imidazole-5-yl[methylane]-2-thiophenepropanoic acid,Smith Kline Beecham Pharmaceuticals, PA); Losartan (DUP753/MK954, DuPontMerck Pharmaceutical Company); Remikirin (RO42-5892, F. Hoffman LaRocheAG); A₂ agonists (Marion Merrill Dow) and certain non-peptideheterocycles (G.D.Searle and Company).

ACE inhibitors include amino acids and derivatives thereof, peptides,including di- and tri-peptides and antibodies to ACE which intervene inthe renin-angiotensin system by inhibiting the activity of ACE therebyreducing or eliminating the formation of pressor substance angiotensinII. ACE inhibitors have been used medically to treat hypertension,congestive heart dysfunction/failure, myocardial infarction and renaldisease. Classes of compounds known to be useful as ACE inhibitorsinclude acylmercapto and mercaptoalkanoyl prolines such as captopril(U.S. Pat. No. 4,105,776) and zofenopril (U.S. Pat. No. 4,316,906),carboxyalkyl dipeptides such as enalapril (U.S. Pat. No. 4,374,829),lisinopril (U.S. Pat. No. 4,374,829), quinapril (U.S. Pat. No.4,344,949), ramipril (U.S. Pat. No. 4,587,258), and perindopril (U.S.Pat. No. 4,508,729), carboxyalkyl dipeptide mimics such as cilazapril(U.S. Pat. No. 4,512,924) and benazapril (U.S. Pat. No. 4,410,520),phosphinylalkanoyl prolines such as fosinopril (U.S. Pat. No. 4,337,201)and trandolopril.

Renin inhibitors are compounds which interfere with the activity ofrenin. Renin inhibitors include amino acids and derivatives thereof,peptides and derivatives thereof, and antibodies to renin. Examples ofrenin inhibitors that are the subject of United States patents are asfollows: urea derivatives of peptides (U.S. Pat. No. 5,116,835); aminoacids connected by nonpeptide bonds (U.S. Pat. No. 5,114,937); di- andtri-peptide derivatives (U.S. Pat. No. 5,106,835); amino acids andderivatives thereof (U.S. Pat. Nos. 5,104,869 and 5,095,119); diolsulfonamides and sulfinyls (U.S. Pat. No. 5,098,924); modified peptides(U.S. Pat. No. 5,095,006); peptidyl beta-aminoacyl aminodiol carbamates(U.S. Pat. No. 5,089,471); pyrolimidazolones (U.S. Pat. No. 5,075,451);fluorine and chlorine statine or statone containing peptides (U.S. Pat.No. 5,066,643); peptidyl amino diols (U.S. Pat. Nos. 5,063,208 and4,845,079); N-morpholino derivatives (U.S. Pat. No. 5,055,466);pepstatin derivatives (U.S. Pat. No. 4,980,283); N-heterocyclic alcohols(U.S. Pat. No. 4,885,292); monoclonal antibodies to renin (U.S. Pat. No.4,780,401); and a variety of other peptides and analogs thereof (U.S.Pat. Nos. 5,071,837, 5,064,965, 5,063,207, 5,036,054, 5,036,053,5,034,512, and 4,894,437).

HMG-CoA reductase inhibitors include, but are not limited to, statinssuch as simvastatin (U.S. Pat. No. 4,444,784), lovastatin (U.S. Pat. No.4,231,938), pravastatin sodium (U.S. Pat. No. 4,346,227), fluvastatin(U.S. Pat. No. 4,739,073), atorvastatin (U.S. Pat. No. 5,273,995),cerivastatin, and numerous others described in U.S. Pat. No. 5,622,985,U.S. Pat. No. 5,135,935, U.S. Pat. No. 5,356,896, U.S. Pat. No.4,920,109, U.S. Pat. No. 5,286,895, U.S. Pat. No. 5,262,435, U.S. Pat.No. 5,260,332, U.S. Pat. No. 5,317,031, U.S. Pat. No. 5,283,256, U.S.Pat. No. 5,256,689, U.S. Pat. No. 5,182,298, U.S. Pat. No. 5,369,125,U.S. Pat. No. 5,302,604, U.S. Pat. No. 5,166,171, U.S. Pat. No.5,202,327, U.S. Pat. No. 5,276,021, U.S. Pat. No. 5,196,440, U.S. Pat.No. 5,091,386, U.S. Pat. No. 5,091,378, U.S. Pat. No. 4,904,646, U.S.Pat. No. 5,385,932, U.S. Pat. No. 5,250,435, U.S. Pat. No. 5,132,312,U.S. Pat. No. 5,130,306, U.S. Pat. No. 5,116,870, U.S. Pat. No.5,112,857, U.S. Pat. No. 5,102,911, U.S. Pat. No. 5,098,931, U.S. Pat.No. 5,081,136, U.S. Pat. No. 5,025,000, U.S. Pat. No. 5,021,453, U.S.Pat. No. 5,017,716, U.S. Pat. No. 5,001,144, U.S. Pat. No. 5,001,128,U.S. Pat. No. 4,997,837, U.S. Pat. No. 4,996,234, U.S. Pat. No.4,994,494, U.S. Pat. No. 4,992,429, U.S. Pat. No. 4,970,231, U.S. Pat.No. 4,968,693, U.S. Pat. No. 4,963,538, U.S. Pat. No. 4,957,940, U.S.Pat. No. 4,950,675, U.S. Pat. No. 4,946,864, U.S. Pat. No. 4,946,860,U.S. Pat. No. 4,940,800, U.S. Pat. No. 4,940,727, U.S. Pat. No.4,939,143, U.S. Pat. No. 4,929,620, U.S. Pat. No. 4,923,861, U.S. Pat.No. 4,906,657, U.S. Pat. No. 4,906,624 and U.S. Pat. No. 4,897,402, thedisclosures of which patents are incorporated herein by reference.

It is to be understood that the invention contemplates the use of one ormore of any of the foregoing agents in combination with the repeated RICregimens of the invention.

RIC

As used herein, an RIC regimen is at least one cycle of an inducedtransient ischemic event followed by a reperfusion event. Typically,these regimens are performed by restricting blood flow in a limb or aperipheral tissue of the subject and then removing the blood flowrestriction and allowing blood to reperfuse the limb or tissue. An RICregimen is typically non-invasive. A regimen may comprise a single cycleor multiple cycles, including 2, 3, 4, 5, or more cycles. In oneimportant embodiment, a regimen comprises 4 cycles of ischemia andreperfusion.

The blood flow restriction typically takes the form of an appliedpressure to the limb or tissue that is above systolic pressure (i.e.,supra-systolic pressure). It may be about 5, about 10, about 15, about20, or more mmHg above (or greater than) systolic pressure. Sincesystolic pressure will differ between subjects, the absolute pressureneeded to induce ischemia will vary between subjects. In otherembodiments the pressure may be preset at, for example, 200 mmHg Theblood flow restriction may be accomplished using any method as theinvention is not limited in this regard. Typically, it may beaccomplished with an inflatable cuff, although a tourniquet system isalso suitable. Further examples of automated devices for performing RICare described below.

The induced ischemic event is transient. That is, it may have a durationof about 1, about 2, about 3, about 4, about 5, or more minutes.Similarly, the reperfusion event may have a duration of about 1, about2, about 3, about 4, about 5, or more minutes. The Examples demonstratethe effect of 4 cycles of 5 minutes of ischemia followed by 5 minutes ofreperfusion on physical performance.

If performed using a limb, the upper limb or lower limb may be usedalthough in some instances the upper limb is preferred. In someinstances, RIC is performed on two different sites on the body, in anoverlapping or simultaneous manner.

RIC may be performed using any device provided it is capable of inducingtransient ischemia and reperfusion, whether manually or automatically.

In one of its simplest forms, the method may be carried out using asphygmomanometer (i.e., the instrument typically used to measure asubject's blood pressure). The cuff of the sphygmomanometer is placedabout a subject's limb (e.g., an arm or leg) and is inflated to apressure great enough to occlude blood flow through the limb (i.e., apressure greater than the subject's systolic blood pressure). The cuffis maintained in the inflated state to prevent blood flow through thelimb for a specified period of time, referred to herein as the ischemicduration. After the ischemic duration, pressure is released from thecuff to allow reperfusion of blood through the limb for a period of timethat is referred herein as the reperfusion duration. The cuff is thenre-inflated and the procedure is immediately repeated a number of times.

The method may similarly be carried out using a manual type tourniquet.Devices such as those described in published PCT application WO 83/00995and in published US application 20060058717 may also be used.

Another system that may be used is described in published US application20080139949. The advantage of this system is that it can be usedindependently of a medical practitioner, and that it automaticallyinduces the required RIC regimen. This system is exemplified in part inFIG. 8, which illustrates a cuff 10, an actuator 12, a controller 14 anda user interface 16. The cuff is configured to be placed about the limb15 of a subject, such as an arm or leg of the subject. The actuator,when actuated, causes the cuff to retract about the limb to occludeblood flow through the limb. The controller executes a protocol thatcomprises repeating a cycle one or more times. The cycle itself includesactuating the cuff to prevent blood flow, maintaining the cuff in anactuated state for an ischemic duration, releasing the cuff, andmaintaining the cuff in a relaxed state to allow reperfusion.

FIG. 9 shows a block diagram that represents a scheme that may be usedto perform RIC. The scheme begins with placement of a cuff about asubject's limb. The system is then activated and the protocol isinitiated through the controller. In one embodiment, the system isactivated by a medical professional. In another embodiment, the systemmay be activated by the subject. The cuff contracts to apply an initialpressure, greater than systolic pressure, to the subject's limb. Asdiscussed herein, the initial pressure may be a default value of thesystem or may be programmed into a particular protocol. The cuff thendeflates to identify the subject's systolic pressure. This may beaccompanied by monitoring the subject for the onset of Korotkoff soundsor vibrations. Alternatively or additionally, a distal remote sensor(e.g., a device on the fingertip which is sensitive to the presence orabsence of flow or maintenance of flow) may be used. Once systolicpressure has been identified, the system initiates the first cycle ofthe protocol. In some embodiments, systolic pressure may be identifiedas an initial portion of the protocol. As used herein, the termsprotocol and regimen are used interchangeably.

The cycle begins as the cuff contracts to apply a target pressure,greater than the subject's systolic pressure by an amount defined in theprotocol, to the subject's limb. This occludes blood flow through thesubject's limb. The external pressure against the subject's limb is heldfor an ischemic duration defined in the protocol. The system monitorsthe subject during the ischemic duration for pressure release criteria,which may include system power failure, system power spikes, and manualactivation of quick release mechanism. The system also monitors thesubject during the ischemic duration for any signs of reperfusionthrough the subject's limb, and accordingly, increases the externalpressure applied by the cuff to prevent such reperfusion. Signs ofreperfusion can include the onset of Korotkoff sounds or vibrations.After passage of the ischemic duration, the cuff releases pressure fromabout the subject's limb to allow reperfusion. Reperfusion is allowedfor a reperfusion duration defined in the cycle.

The initial cycle typically concludes after the reperfusion duration. Atthis time, a subsequent cycle may begin as the cuff is actuated tocontract about the subject's limb to occlude blood flow through the limbfor another ischemic duration.

The cuff illustrated in FIG. 8 is configured to be positioned about thelimb of a subject and to contract about the limb when actuated. In oneembodiment, the sleeve is wrapped about a subject's upper arm, calf, orthigh and is fastened snuggly in place. Portions of the cuff may includehook and loop type material that can be used to fasten the sleeve inplace about the subject's limb. The actuator inflates the cuff such thatthe limb is constricted to the point of occluding blood flow through thesubject's limb.

The illustrated cuff includes an inflatable bladder (not shown) thatreceives a fluid, such as air, to cause the cuff expand and retractabout a subject's limb. The bladder is constructed of an air impermeablematerial, such as flexible plastic or rubber. A connection port 18 ispresent at one end of the bladder to allow air to enter the bladderduring inflation, or to exit the bladder during deflation. The port mayinclude engagement features to facilitate a connection to the actuator,such as by an air hose. These features may include threads, clips, andthe like. Although the illustrated embodiment includes a single bladderpositioned within a cuff, it is to be appreciated that other embodimentsare also possible. By way of example, according to some embodiments, thefabric sleeve may itself be air impermeable, such that no separatebladder is required. In other embodiments, multiple, separate inflatablebladders may be incorporated into a common sleeve, as aspects of thepresent invention are not limited in this respect.

The general size of subjects that undergo RIC may vary greatly,particularly given the range of species to which the methods may beapplied. Given this variance, it may be desirable for some embodimentsof cuffs to be adjustable over a wide range to accommodate the varietyof subject limb girths that may be expected. According to someembodiments, the cuff comprises an inflatable fabric sleeve having alength greater than three feet, such that a girth of up to three feetmay be accommodated. Embodiments of cuffs may include a width as smallas two inches, one inch, or even smaller, so as to accommodate the upperarm or leg of a much smaller subject, including a neonatal infant. It isto be appreciated, however, that other embodiments may be configured toencircle a much smaller range of limb sizes, as aspects of the presentinvention are not limited in this regard.

Various devices may be used as an actuator to constrict the cuff about asubject's limb, or to release the cuff. As illustrated in embodiment ofFIG. 8, the actuator includes a pneumatic pump to provide pressurizedair to an inflatable cuff through an air hose. The actuator alsoincludes a release valve 20 that, when actuated, opens a passagewaybetween the inflatable cuff and the external environment to allowpressurized air to escape from the cuff, so that the cuff loosens aboutthe subject's limb.

The air pump can comprise any device capable of delivering compressedair. According to some embodiments, the air pump includes a pistoncompressor, although other types of pumps, like centrifugal pumps andscroll compressor may also be used. The pump may be configured toprovide air flow at a rate of between 0.1 to 20 cubic feet per minute,with a head pressure of up to 50 psi, according to some embodiments.However, other flow rates and/or pressures are possible, as aspects ofthe invention are not limited in this respect.

As discussed above, the actuator may also include a release mechanism torelease a cuff from about the subject's limb. In the illustratedembodiment, the release comprises a release valve 20 that is positionedwithin the controller housing. The release valve, as shown, may be asolenoid that moves rapidly between fully closed and fully openpositions to rapidly release air from the cuff and, in turn, to rapidlyrelease the cuff from a subject. According to some embodiments, the samerelease valve or another release valve may also be actuated to openslowly, such as to adjust the pressure of the cuff or to allow a morecontrolled release of pressure such as may be required when thesubject's blood pressure is measured.

Embodiments of the system may include safety features to allow rapidrelease of the cuff from a subject's limb. Moreover, some of theseembodiments may be readily activated by a subject, such as when thesubject feels discomfort. In one embodiment, the safety release 22includes a large button positioned on or near the cuff. In this regard,the safety release is within reach of the subject. In other embodiments,the safety release may comprise a separate actuator, such as one thatmay be held in the free hand of the subject. Activating the safetyrelease may cause the release valve of a pneumatic cuff to open, therebyallowing rapid removal of air from the cuff.

The system may also include a continually operating, cuff releasemechanism. By way of example, a slow release valve may be incorporatedinto a pneumatic cuff to provide for a continual, slow release ofpressurized air from the cuff. The continual slow release mechanism mayprovide for the safe release of a subject's limb, even in the face ofpower failures or other events that may prevent redundant safetyfeatures from operating properly. Similar type mechanism may beincorporated into embodiments that do not utilize a pneumaticallyinflatable cuff, as continual slow release mechanisms are not limited topneumatic cuffs. The system may also comprise a pressure check valve asa safety feature. Such a valve may operate by releasing pressure above amaximum set point. The maximum set point will be at or above thesupra-systolic pressures used during remote ischemic conditioning, andmay be but is not limited to 200 mmHg, 210 mmHg, 220 mmHg, 230 mmHg, 240mmHg, or 250 mmHg The system may also comprise software and/or hardwarecomponents that monitor pressure (e.g., the cuff pressure and/or thesubject blood pressure) and preferably read out such pressuremeasurements whether in real-time or after the remote ischemicconditioning is complete. In this way, deviations in pressure can beidentified.

Embodiments of the system include a controller that receives informationfrom a protocol and any other sensors in the system to, in turn, controlthe actuator to perform RIC. The controller and protocol combination maybe implemented in any of numerous ways. For example, in one embodimentthe controller and protocol combination may be implemented usinghardware, software or a combination thereof. When implemented insoftware, the software code can be executed on any suitable processor orcollection of processors, whether provided in a single computer ordistributed among multiple computers. It should be appreciated that anycomponent or collection of components that perform the functionsdescribed herein can be generically considered as one or morecontrollers that control the functions discussed herein. The one or morecontrollers can be implemented in numerous ways, such as with dedicatedhardware, or with general purpose hardware (e.g., one or moreprocessors) that is programmed using microcode or software to performthe functions recited above. The one or more controllers may be includedin one or more host computers, one or more storage systems, or any othertype of computer that may include one or more storage devices coupled tothe one or more controllers. In one embodiment, the controller includesa communication link to communicate wirelessly, or via electrical oroptical cable, to a remote location.

In this respect, it should be appreciated that one implementation of theembodiments of the present invention comprises at least onecomputer-readable medium (e.g., a computer memory, a floppy disk, acompact disk, a tape, etc.) encoded with a protocol in the form of acomputer program (i.e., a plurality of instructions), which, whenexecuted by the controller, performs the herein-discussed functions ofthe embodiments of the present invention. The computer-readable mediumcan be transportable such that the protocol stored thereon can be loadedonto any computer system resource to implement the aspects of thepresent invention discussed herein. In addition, it should beappreciated that the reference to a protocol or controller which, whenexecuted, performs the herein-discussed functions, is not limited to anapplication program running on a host computer. Rather, the termprotocol is used herein in a generic sense to reference any type ofcomputer code (e.g., software or microcode) that can be employed toprogram a processor to implement the herein-discussed aspects of thepresent invention.

The system may also comprise one or more sensors 26 that receiveinformation from the subject and/or portions of the system itself. Suchsensors may receive information regarding blood flow in any portion ofthe subject, including the limb that is being treated. These sensors mayalso receive information regarding other operating parameters of thesystem, such as air pressure within a pneumatic cuff, direct readings ofpressure applied by cuff, or tension within portions of a tension band.

Pneumatic cuffs may include a sensor to measure pressure within thecuff. Cuff pressure is often directly indicative of the pressure thatexists within a blood vessel of the limb beneath the cuff. Thecontroller of a system is often programmed to target a particular cuffpressure that is to be maintained during the ischemic duration of acycle, as is discussed herein. In embodiments that include a pneumaticcuff, the pressure sensor may be positioned anywhere within thepressurized space of the cuff, the air hose, or even within the actuatoritself. Pressure sensors may also be positioned on an inner surface ofthe cuff to directly measure the pressure between the cuff and an outersurface of the subject's limb. In use, the cuff may be oriented suchthat the pressure sensor is positioned directly above the subject'sartery, so as to provide a more direct measurement of pressure at ablood vessel of interest. Reference can be made to Noordin et al. J BoneJoint Surg Am, 2009, 91:2958-2967 which discusses the relationship ofcuff width, circumference and pressure on measurements of bloodpressure.

In one embodiment, systems may also include one or more vibration and/orultrasonic sensors 28 to identify Korotkoff sounds. Korotkoff sounds aregenerally understood to be present when pressures between systolic anddiastolic are externally applied to the artery of a subject. Systolicpressure is associated with a pressure value that completely occludesblood flow through a subject's blood vessels, and in this regard, may beused by the system as feedback to identify when pressure in the systemis low enough to allow blood flow, or high enough to occlude blood flow.

One or more sensors may be included to confirm the cessation of bloodflow or reperfusion in the limb that receives the cuff. For instance, insome embodiments, a pulse oximeter 30 may be positioned on a distalportion of the limb that receives the cuff, such as on a finger or toeof the limb. The pulse oximeter can provide information regarding bloodpulsing through the subject's blood vessels and the percentage ofhaemoglobin that is saturated with oxygen. The pulse oximeter willdetect an absence of pulses when blood flow though a limb is notoccurring to confirm the occlusion of blood flow. Moreover, the pulseoximeter may also detect the percentage of haemoglobin saturated withoxygen, which will drop as blood flow through the limb ceases. It is tobe appreciated that other sensors may also be used to confirm thecessation of blood flow, such as a photoplethysmographic transducer, anultrasonic flow transducer, a temperature transducer, an infrareddetector, and a near infrared transducer, as aspects of the inventionare not limited in this respect.

As mentioned above, the system includes a protocol that, through thecontroller, directs the operation of the system. Embodiments of theprotocol include a cycle that comprises cuff actuation, an ischemicduration, cuff release, and a reperfusion duration. In many embodimentsof protocols, the cycle may be repeated multiple times. Additionally,some embodiments of the protocol include systolic pressureidentification.

The cuff actuation portion of the cycle comprises contracting the cuffabout the limb of a subject to occlude blood flow through the limb.Contraction of the cuff is accomplished by the controller readinginstructions from the protocol, such as a target set point for cuffpressure, and then by the initiating the controller to bring the cuff tothe target set point. Attainment of the target set point may be sensedthrough any of the herein described sensors and techniques.

During the ischemic phase of the cycle, pressure is maintained about thesubject's limb to prevent reperfusion of blood flow through the limb.The length of the ischemic phase, termed the ischemic duration, istypically defined by a doctor, or other medical professional, and isprogrammed into the protocol. Ischemic duration may be as short as a fewseconds, or as long as 20 minutes, or even longer, as aspects of theinvention are not limited in this regard. In some embodiments, theischemic duration varies from cycle to cycle during the same protocol,although in other embodiments, the ischemic duration remains constant.

The controller acts to maintain pressure, applied by the cuff, at a setpoint above the subject's systolic pressure. Embodiments of the cuff mayrelax relative to the subject's limb over time, thereby reducingpressure and eventually allowing reperfusion. This may be caused byvarious factors, including relaxation of muscles in the subject's limb,stretching of the cuff about the limb, air leaks (intentional orunintentional), and the like. To this end, a sensor may provide pressurereadings as feedback to the controller. The controller can measure anydifference between the set point and the actual pressure reading and canprovide any necessary commands to the actuator to compensate for errors.

Various approaches may be used to define an appropriate set point forthe controller during the ischemic duration. According to oneembodiment, the set point is manually entered into the protocol by thedoctor (or other medical professional). Alternately, the doctor mayselect a set point in terms of the subject's systolic blood pressure. Inone embodiment, the set point may be selected as a fixed pressure amountover the subject's systolic blood pressure, such as 5 mmHg, 10 mmHg, 15mmHg, 20 mmHg, 25 mmHg, 30 mmHg, 35 mmHg, or any other fixed amountabove systolic pressure of the subject. In other embodiments, the setpoint may be defined as a percentage of the subject's systolic bloodpressure, such as 101%, 102%, 103%, 104%, 105%, 106%, 107%, 108%, 109%,110%, 111%, 112%, 113%, 114%, 115% or systolic pressure and otherpercentages, as aspects of the invention are not limited in thisrespect. The point above systolic pressure may be set by the medicalprofessional and may be dependent upon several factors including, butnot limited to the size of the subject, the size of the subject's limb,the subject's blood pressure, confirmation of blood flow cessation, andthe like.

The protocol, according to some embodiments, includes phases to identifythe subject's systolic blood pressure. The cuff may be allowed to loosenabout the subject's limb, from a point believed to be above systolicpressure, in a systematic manner while sensors are monitoring the limbfor the onset of Korotkoff sounds or vibrations. Once the systolicpressure is identified, the protocol may continue in the normal course.

Identification of systolic pressure may optionally occur at any timeduring a protocol, or not at all. According to some embodiments, eachcycle begins with the identification of the subject's systolic bloodpressure. In other embodiments, systolic pressure may be identified onlyonce during an initial portion of the protocol. In still otherembodiments, systolic pressure may be identified as the cuff is releasedduring the cuff release portion of each cycle. Still, as discuss herein,systolic pressure may not be identified at all during a protocol, asaspects of the invention are not limited in this regard.

The system can be configured to adjust the pressure set point during theischemic duration. As discussed herein, the system may include sensorsthat detect the onset of reperfusion. As an example, this may beaccomplished by detecting the presence of Korotkoff sounds orvibrations. The presence of Korotkoff sounds during an ischemic durationcan indicate that either cuff pressure has fallen below systolic or thatsystolic pressure has risen above the set point that was previouslyabove systolic pressure. Other devices may additionally or alternativelybe used including for example devices on digits that detect the presenceor absence of flow. In such a situation, the controller may adjust theset point based on the newly identified systolic pressure and/or otherinformation and in this regard, can identify and prevent unwantedreperfusion that might otherwise occur.

The cuff release portion of a cycle occurs at the end of the ischemicduration and includes release of the cuff to a point below diastolicpressure. According to some embodiments, cuff release comprisesreleasing the pressure or tension of the cuff. In embodiments thatutilize a pneumatic cuff, this may simply be associated with moving anair release valve to the fully open position to allow a rapid reductionin cuff pressure and a corresponding rapid relaxation of the cuff aboutthe subject's limb. However, it is to be appreciated, that in otherembodiments, that cuff relaxation may occur in a slower, more controlledmanner, as aspects of the invention are not limited in this respect.Additionally, as discussed herein, the cuff release may be accompaniedby monitoring for the onset of Korotkoff sounds or vibrations toidentify or confirm the systolic pressure of the subject.

The reperfusion duration follows the cuff release in embodiments of thecycle. Reperfusion through the limb is allowed for a period of timetermed the reperfusion duration. Much like the ischemic duration,reperfusion may be allowed for varied lengths of time, as short as afive seconds, one minute or more, and as long as 20 minutes, or evenlonger. The reperfusion duration may remain constant from cycle to cycleduring a common protocol, or may vary between each cycle, as aspects ofthe invention are not limited in this respect.

The protocol may comprise any number of cycles. As discussed herein, acommon cycle may simply be repeated a plurality of times, such as two,three, four, or more times, to complete a protocol. Alternately, thecycles of a protocol may be programmed with different parameters, suchas different ischemic durations, reperfusion durations, pressure setpoints during the ischemic duration, and the like.

In some embodiments, the system may include a data logging feature thatrecords the system parameters, such as cuff pressure or tension, duringall phases of a protocol. Date of time of operation may also berecorded. Other features, such as personal information to identify thesubject, may also be recorded by the system.

Embodiments of the system may incorporate various features to inform thesubject or medical professional about the progress of the protocol.Audible or visual indicators may accompany any of the phases of theprotocol. By way of example, a clock may show either the amount of timethat has elapsed or that remains for a given portion of the protocol orthe entire protocol. Embodiments may also include other features to keepthe subject and/or medical professional informed, as aspects of theinvention are not limited in this regard.

According to some embodiments, the system includes features to preventtampering or accidental reprogramming by a subject. By way of example,in some embodiments, the reprogrammable features may only be accessedafter entering a code. This can prevent a subject from mistakenlyreprogramming the protocol or otherwise interfering with the operationof the system. It is to be appreciated that other devices may also beused to prevent accidental reprogramming, such as electronic keys,mechanical locks and the like.

The system may be configured for use is a variety of environments. Byway of example, the system may be mounted on a portable stand withcasters to facilitate easy movement. The stand may position thecontroller, user interface, and connections to the cuff at a convenientheight for the subject. In other embodiments, the system is configuredfor portable use. In such embodiments, the system may be configured forready placement into a suitcase for easy transport.

The system is also not limited to components illustrated in theembodiment of FIG. 1. By way of example, according to other embodiments,like that illustrated in FIG. 10, cuffs may be configured to constrict asubject's limb through alternative mechanisms. In the illustratedembodiment, the cuff is configured as a band having a ratchetingmechanism positioned at one end. In use, the band is wrapped about thelimb of a subject with the free end of the band passing through theratcheting mechanism. In such an embodiment, the actuator may comprise amechanism that pulls the free end of the band further through theratcheting mechanism to retract the cuff about the limb, or that freesthe ratcheting mechanism to release the band to, in turn, release theband from the limb. Still other mechanisms, such as tourniquetmechanisms, are possible, as aspects of the invention are not limited inthis respect.

As described above with reference to FIG. 10, some embodiments may havea cuff that comprises a band that does not inflate, but rather istightened about a subject's limb by another mechanism. In suchembodiments, the actuator may comprise a tensioning mechanism configuredto move one end of the band relative to other portions of the band so asto place the band in tension. As shown, the mechanism can includeopposed rollers held in close proximity to one another within a housing.The housing includes a slot for receiving a free end of the band and afixation point for fixed attachment to the opposite end of the band. Thefree end of the band is passed into the slot and between the rollers.The rollers may be mechanically actuated to rotate relative to oneanother, such as by an electric motor, to pull the free end through thehousing and thus tighten the band around a subject's limb.

The tensioning mechanism may include opposed rollers mounted on aratcheting, free wheel mechanism. The freewheel mechanism allows theband to be pulled through the slot in one direction with minimalresistance so that the band may be pulled rapidly to a snug positionabout a subject's limb. The free wheel mechanism also prevents the bandfrom moving through the slot in the loosening direction, unless themechanism is released or the opposed rollers are actuated. It is to beappreciated that not all embodiments will include a free wheelmechanism, as aspects of the invention are not limited in this regard.

The opposed rollers rotate in either direction to tighten and loosen theband during use. When required, the rollers may rapidly rotate until theband achieves a particular tension. The rollers may further be actuatedto make minor adjustments to the tension in the band during use. Whenthe cuff is to be released from the subject's limb, a ratchetingmechanism or clutch may be released such that the opposed rollers areallowed to move freely, thus rapidly releasing tension.

The system and/or device may comprise disposable components to preventcontamination between subjects and to avoid the need to sterilize thesystem or device between subjects. The entire system or device may bedisposable or one or more of its components may be disposable.Disposable component include but are not limited to the cuff(s) of thesystem and/or sleeves or liners for the cuff(s).

Aspects of the invention are not limited to the embodiments of cuffsillustrated herein.

EXAMPLES Materials and Methods

Animals. Fifty eight week-old male Sprague-Dawly (SD) rats, weighingbetween 250 g and 280 g (Experimental Animal Center, Fudan University,Shanghai, P.R. China) were studied. The animal research study protocolwas in compliance with ‘The Guide for the Care of Use of LaboratoryAnimals’ published by the National Institute of Health (NIH PublicationNo. 85-23, revised 1996) and approved by the Animal Care Committee ofShanghai Sixth Hospital, Shanghai Jiao Tong University School ofMedicine. All the rats were housed for two weeks for an acclimatizationperiod before the experiments.

Surgical Preparation. After anesthesia with sodium pentobarbital (40mg/kg, IP) and endotracheal intubation, animals were ventilated (AnimalRespirator DW-2000, Aloctt Biotech, Shanghai, P. R. China) with roomair. The heart was exposed through a thoracotomy at the left fourthintercostal space. The left anterior descending coronary artery (LAD)was encircled by a 6-0 prolene suture 1 to 2 mm below the tip of theleft atrial appendage and its ends were threaded through a polyethylenetubing (PE-50) to form a snare for reversible coronary artery occlusion.Prior to LAD occlusion, the animals were anticoagulated (150 U/Kg sodiumheparin) and received an intravenous injection of lidocaine (4 mg/Kg).Cardiac ischemia was confirmed by a pale area below the suture or ST-Televation shown in ECG, while reperfusion was characterized by rapiddisappearance of cyanosis and vascular blush. At the end of theprotocol, the snare was removed, the chest closed, and the animalsallowed to recover, and they were given tamgesic (0.03 mg/kg)immediately before they gained consciousness.

Experimental Protocol. After anesthesia, all rats were randomly assignedto the following six experimental groups:

1) MI group (MI control), MI was created with 45 minutes LAD ligationfollowed by reperfusion for long term observation;

2) Single remote ischemic post-conditioning (sPost) group (also referredto herein as rIPerC), during the ischemia reperfusion injury surgicalprocedure, while the animals were anesthetized remote ischemicpost-conditioning was delivered starting 20 minutes before the end ofindex ischemic period by occluding hind limb blood flow with a torniquettightened around the upper thigh for 4 cycles of 5 minutes occlusionfollowed by 5 minutes release. The limb ischemia was confirmed by pallorand cyanosis of the lower limb below the torniquet;

3) Delayed post-conditioning (dPost) group, the delayed remotepost-conditioning was delivered on day 4 (72 hours after reperfusion).Rats were anesthetized again with smaller dosage of sodium pentobarbital(30 mg/Kg). The remote post-conditioning was delivered the same way asdescribed above. Tamgesic (0.03 mg/kg) was also given before theyregained consciousness;

4) Repetitive remote post-conditioning (rPost) group (also referred toherein as rPostC), after the initial remote post-conditioning (identicalto group 2), post-conditioning was repeated every three days for 28days, and therapy was delivered the same way as described in dPost grouprats;

5) Intensive remote post-conditioning (iPost) group (also referred toherein as iPostC), after the initial remote post-conditioning (identicalto group 2), the same remote post-conditioning therapy as describedabove was repeated every day for 28 days;

6) Sham group, rats underwent sham operation without suture tie-down.All the surviving rats that completed the observation period weresacrificed either on day 4 (72 hours after reperfusion), I also havemarked this on protocol figure), or on day 28 after reperfusion,respectively for testing outlined below, and detailed in FIG. 1.

For day 4 and day 28 studies, animals assigned to the remote ischemicpost-conditioning therapy on either day 4 or day 28 were euthanized 2hours after the episode of post-conditioning. Both echocardiographic andinvasive hemodynamic examination (described as below) was performed toevaluate the remodeling process immediately before euthanization.

After euthanization, whole blood was then collected from inferior venacava and the heart was harvested. A careful autopsy was performed foreach rat, including those who experienced sudden cardiac death,particularly in regard to possible cardiac rupture. After autopsy, LVweight was recorded for hearts obtained from day 28 and the ratio of LVweight to body weight (LVMI) was calculated. One cross-section of LVmyocardial tissue at the level of the papillary muscles, approximately 5mm, was collected and fixed in 4% formalin followed by paraffinembedding for the histology examination. The remaining LV tissue wassnap frozen in liquid nitrogen and stored at −80° C. for later analysis.

Survival Study. To evaluate the survival rate, another total 250 ratswere assigned to MI group, RIPerC group, rPostC group, iPostC group andSP group (50 rats for each group) while 25 sham operated rats acted ascontrols. All the rats were rigorously monitored for 12 weeks. A carefulautopsy was performed for each rat searching for the cause of suddendeath, especially in reference to cardiac rupture. Survival rate wasanalyzed to evaluate the long term benefits of the treatments.

Echocardiography and Hemodynamic Study. Transthoracic echocardiographywas performed only on day 28 after MI. using ultrasonic system equippedwith a 15-MHz probe (Acuson Sequoia 512). Both two-dimensional andM-mode echocardiography was obtained after the induction of anesthesia.LV end diastolic diameter (LVEDD) and LV end systolic diameter (LVESD)was measured in short axis view at papillary muscle level. Thefractional shortening (FS) was also calculated. All the values wereaveraged over five consecutive cardiac cycles and measurements wereanalyzed by two independent researchers blinded to treatment protocol.Thereafter, cardiac catheterization was performed in animals forhemodynamic study. The right carotid artery was cannulated with apre-heparinized fine polyetheylene tube connected to a fluid-filledpressure transducer (MPA-CFS, Alcott Biotech, Shanghai, China) and thetube was then advanced into the left ventricle. Heart rate (HR), leftventricular peak systolic and end-diastolic pressure (LVEDP) and themaximal rates of rise and fall in LV pressure (dP/dt_(max) anddP/dt_(min), respectively) were recorded.

Myocardial Infarct Size Determination. On day 4 (72 hours afterreperfusion), the LAD was re-occluded and 1 ml 1% Evan's blue wasperfused into the aorta and coronary arteries. The heart was thenisolated, perfused with PBS and sliced transversely in a planeperpendicular to the apical-basal axis into 8 mm thick sections. Heartsections were then incubated in 1% 2,3,5-triphenyltetrazolium chloride(TTC) (Sigma) for 5 to 10 min at 37° C. The infarct area (pale), thearea at risk (red), and the total LV area from each section weremeasured using Image J software. Infarct size, expressed as apercentage, was calculated by dividing the sum of infarct areas weightfrom all sections by the sum of LV risk area weight from all sectionsand multiplying by 100.

To measure infarct size 28 days after MI, the LV area was estimatedusing a slice obtained from the central part of the myocardium at thelevel of the papillary muscles. The infarct (expressed as fibrotic area)perimeter was traced and the size of MI was normalized to LV area usingthe following equation: percentage Infarct perimeter (IP)=Circumferenceof Infarct Scar/[(Epicardium Perimeter+EndocardiumPerimeter)/2]×100%^([22]).

Histological Analysis. Deparaffinized tissue sections were prepared forimmunohistochemical staining. First antibody against Myeloperoxidase(MPO, 1:50 dilution, Abcam), against ED-1 (a specific marker formacrophage, 1:100 dilution. Chemicon) and Monocyte chemoattractantprotein-1 (MCP-1, 1:100 dilution, Abcam) were performed for neutrophiland macrophage infiltration quantification, using heart tissue obtainedfrom day 4. Antibody against 8-Hydroxyguanosine (8-OhdG, 1:300 dilution,Abcam) was also used for quantifying oxidative stress mediated DNAinjury, using heart tissue obtained from day 28. Sections incubated withsecondary antibody alone served as negative control. All sections werecounterstained with hematoxylin.

Collagen deposition in the border area was quantified by Masson-stainingand analyzed by using Image J software and expressed as the averagepercentage collagen staining of 10 randomized high power field.

In addition, the hematoxylin-eosin stained sections from the centralportion of the LV was obtained to evaluate myocyte cross-sectional area(CSA) in those centrally-nucleated cells cut transversely. The CSA wasmeasured and averaged of 50 cells in the posterior wall (non-infarctedarea) of the LV from each sample, and a total four samples were analyzedfor each group.

Western Blot. Equal amounts of protein (50 μg) were separated on 8-16%Tris-glycine gel (Novex, Invitrogen, CA, USA) and transferred to a PVDFmembrane. After blocking with 5% skim milk, primary antibody againstphospho-Smad2, phospho-IκB-α (Ser32), IκB-α, phospho-NF-κB-P65,NF-κB-P65 (Cell Signaling Tech, USA), and TGF-β1 and Smad2 (Santa Cruz,USA) were incubated overnight at 4° C. followed by incubation withhorseradish peroxidase conjugated secondary antibody either anti-mouseor anti-rabbit (1:2000) Immuno-reaction was finally visualized using anECL detection Kit (Amersham, Beverly, Mass., USA). All the proteinexpression level was adjusted for GAPDH intensity (Cell Signaling Tech,USA). Bands were quantified by densitometry using the software of ImageJ (version 1.41, NIH, USA).

Real Time RT Polymerase Chain Reaction. Total RNA was prepared from 150mg of LV tissue using Trizol reagent (Invitrogen) followed by chloroformextraction and isopropanol precipitation. Genomic DNA was eliminated byincubating with DNase I (0.1 μl⁻¹, 37° C.) for 30 min followed by acidphenol-chloroform extraction. RNA was quantified by spectrophotometricabsorbance at 260 nm, with its purity confirmed by A₂₆₀/A₂₈₀ ratio andintegrity evaluated by ethidium bromide staining on a denaturing agarosegel. Total RNAs (2 μg) were then reverse transcribed using oligo(dT)primer and Superscript II reverse transcriptase (RT, Invitrogen).

Real time PCR quantification was performed starting with 12.5 ng cDNAand both sense and antisense primer at 900 nM concentration (Invitrogen)in final volume of 25 μl, using SYBR Green master mix (AppliedBiosystem). Fluorescence was monitored and analyzed in a GeneAmp 7000detection system instrument (Applied Biosystems). The PCR reactions werecycled 42 times by a three-step cycle procedure (denaturation 95° C., 15s; annealing 60° C., 30 s; extension 72° C., 30 s) following the initialstage (95° C., 10 min). A ΔCt value was obtained to quantify the mRNAlevels and normalized with an endogenous control (b-tubulin mRNA) foreach sample. A relative quantification ΔΔCt method was used forcomparison between groups. Oligonucleotide primers were designed usingPrimer Express software (Applied Biosystems).

The primers used were listed as follows:

(SEQ ID NO: 1) α-MHC, sense (CTGCTGGAGAGGTTATTCCTCG) and (SEQ ID NO: 2)antisense (GGAAGAGTGAGCGGCGCATCAAGG); (SEQ ID NO: 3) β-MHC, sense(TGCAAAGGCTCCAGGTCTGAGGGC) and (SEQ ID NO: 4) antisense(GCCAACACCAACCTGTCCAAGTTC); (SEQ ID NO: 5) ANP, sense(CTCTGAGAGACGGCAGTGCT) and (SEQ ID NO: 6) antisense(TATGCAGAGTGGGAGAGGCA); (SEQ ID NO: 7) β-tubulin, sense(TCACTGTGCCTGAACTTACC) and (SEQ ID NO: 8) antisense(GGAACATAGCCGTAAACTGC).

Determination of Malondialdehyde (MDA) Level. Myocardium obtained fromthe area at risk was homogenized in 1.0 ml of 20 mmol/L Tris-HCl, pH7.4, containing 5 mmol/L butylated hydroxytoluene. Lipid peroxides wereassayed using a commercial available kit (Cat #437639, Calbiochem)according to the manufacturer's introduction, and level of MDA wasexpressed as μM per gram protein.

Cytokine Levels. Plasma levels of interleukin TNF-α and IL-1β wereevaluated by use of commercially available solid-phase sandwich ELISAkits (R&D Systems, Minneapolis, USA) according to the manufacturer'sintroduction. The detection limits of each assay were as follows:TNF-α,16 pg/ml and IL-1β, 10 pg/ml.

Statistics. All values were expressed as mean±SD. All data analysis wasperformed with the use of SPSS 13.0 statistical software. One-way ANOVAfollowed by multiple comparisons with Student-Newman-Keuls test was usedto determine the effects of treatments on the various parameters.Survival rates during follow up among the six groups were analyzed bystandard Kaplan-Meier analysis, and a statistical comparison betweensurvival curves was made with the log-rank test. Fisher's exact methodis used to analyze the differences in survival rate between the groups.Statistical significance was defined as P<0.05.

Results

Improved survival rate by intensive post-conditioning. During the 84 dayobservation period, rIPerC (or sPost), rPostC (or rPost) and iPostC (oriPost) resulted in improved survival rate compared with MI and SP groups(P<0.05, for all). Interestingly, the improved survival rate wasapparent as early as 28 days after MI only in the iPostC group whereasin rPostC group this effect was not observed until 56 days after MI.Furthermore, on day 84 iPostC was associated with improved survival ratecompared with RIPerC and rPostC treatments (P<0.05, respectively). Dailydelivery of sodium pentobarbital did not offer any beneficial or adverseeffects during the observation period compared with MI group (P>0.05)(FIG. 11). Autopsy in those animals who died showed no incidence ofcardiac rupture in the treated groups, 1 in the SP group and 1 in the MIgroup, with no statistical significance between the different groups(P>0.05, respectively).

Early Phase of Protection against Reperfusion Injury. There was atendency to reduced sudden death during the first seventy-two hours inthe sPost, rPost and iPost treated groups compared with MI group,however it was not statistically significant (See Table, P>0.05,respectively). Thorough autopsy examinations did not reveal any findingsof cardiac rupture in any of the animals. Infarct size was quantifiedfor 8 rats from each group. Area at risk delineated by Evans blue wassimilar between the five groups (data not shown). There was asignificant decrease in infarct size in sPost group rats (35.63±4.21%),rPost group rats (33.88±3.52%) and iPost group rats (31.88±4.82%) (allP<0.05), however, the infarct size was not significantly differentbetween these three Post groups (P>0.05, respectively), indicating thatrepetitive remote post-conditioning treatment has no additional effecton infarct size over a single episode of post-conditioning. In contrast,compared with MI group (50.5±4.11%) dPost when delivered 2 hours beforeeuthanization (on day 4) failed to modify infarct size (42±4.54%,P>0.05).

Early Phase Inflammatory Response Modulated by Post-Conditioning. On day4 (72 hours after reperfusion), five hearts were collected from eachgroup respectively for immunohistochemical staining, macrophages andneutrophils infiltration into the infarcted area was minimal in the shamgroup using antibody targeting ED-1 and MPO (FIG. 2A), respectively.There was intensive infiltration by both macrophages and neutrophilsdetected in infarcted myocardium (ED-1 cells, 1722±217/mm²; MPO cells,880±144/mm p<0.001, respectively), which was attenuated in sPost rats(p<0.001, respectively; FIG. 2B). Macrophage and neutrophil infiltrationwas further attenuated by rPost and iPost (p<0.001, respectively) withthe greatest effect detected in iPost group rats ((p<0.001; FIG. 2B).

The expression level of MCP-1 in the infarcted area showed exactly thesame pattern as the macrophage and neutrophil infiltration,demonstrating a dose-dependent effect of rIPost on inflammatory cellresponses (p<0.001, respectively; FIG. 2C). dPost when delivered 2 hoursearlier before examination did not show any modification in inflammatoryresponses (FIG. 2).

Late Phase Protection by Post-Conditioning. There were fewer survivorson day 28 in the MI group and dPost group compared with sham group(P<0.05, respectively), whereas sPost and repeated post-conditioning(rPost and iPost) treated groups rats showed no significant differencein comparison with sham group rats (See Table, P>0.05, respectively).The infarct size in the survivors to 28 days, demonstrated a similarpattern as on day 4 (p<0.05, respectively, Table 1).

Late Phase Oxidative Stress and Inflammatory Response. DNA damageinduced by oxidative stress was evaluated by 8-OHdG immunostaining. Theexpression of 8-OHdG was increased in MI rats on day 28, rIPost alsoresulted in a significant dosage dependent reduction in 8-OHdG intensity(FIG. 3A), whereas dPost did not affect the 8-OHdG expression (FIG. 3A).

MDA measurement recapitulated the changes of intensity of 8-OHdG (FIG.3B). However, while sPost did not modify TNF-α and IL-1β levels on day28 (p>0.001, respectively), they were attenuated by repeated by bothiPost and rPost groups, and to the same degree (p<0.001, respectively,FIG. 3C).

Activation of Transcription Factor NF-κB. By comparison with the MIgroup, sPost was associated with less IκBα and NF-κB p65phosphorylation. Both rPost and iPost were associated with a furtherdecrease in the degree of IκBα and NF-κB p65 phosphorylation (p<0.001,respectively), with iPost group rats showing the lowest activation ofNF-κB signaling (p<0.01, respectively, FIG. 4).

Fibrosis Responses Modulated by Repeated Post-Conditioning. Themodulation of TGF-β1/Smad2 signaling activation by rIPost was consistentwith the beneficial effects pattern of the NF-κB signaling activation(FIG. 5), which was further supported by attenuated interstitialfibrosis shown in Masson trichrome staining (FIG. 6).

Hypertrophic Response. The increase in LVMI seen in the MI group wasattenuated by sPost (p<0.05; Table). A further decrease was detected inboth rPost and iPost, with the lowest LVMI observed in iPost (p<0.001,respectively, Table).

Going along with this, the average cross-sectional area (CSA) of cardiacmyocytes decreased in dose-dependent fashion (FIGS. 7A,B).Quantification of hypertrophy-related genes expression showed thatincreased gene expression of ANP and β-MHC was attenuated while thedecrease in expression of α-MHC was recovered by rIPost, again in adosage dependent fashion (FIGS. 7C-E). However, the effects were absentwhen the maneuver was delayed to 72 hours after reperfusion (FIGS.7A-E).

Improved Cardiac Geometry, Function and Hemodynamic Parameters. On day28, MI rats demonstrated significant LV dilation, as evidenced byincreases in LVEDD compared with sham rats (p<0.05, table). Thisgeometric change was accompanied by decrease in FS compared with shamrats (p<0.05, table). While sPost significantly improved adverse LVremodeling, reflected by a decrease in LVEDD and an increase in FScompared with MI rats (p<0.05, respectively. Table), rIPost therapyresulted in a further improvement in LV chamber size and function, withthe greatest effects achieved by iPost in comparison with rPost (p<0.05,respectively). Hemodynamic analysis demonstrated the same pattern ofbenefits from rIPost, in a dose-dependent manner compared with MI anddPost (Table).

Discussion

This is the first study to demonstrate that remote conditioning improveslate LV remodeling and survival in a dose dependent manner. The datashow that a single early episode of remote per-conditioning, initiatedduring the final 20 minutes of ischemia and continuing into thereperfusion period, can afford long term protection against LVremodeling after MI, as evidence by attenuated LV dilation and improvedcardiac function, and less myocardial hypertrophy and fibrosis. Thiseffect is lost, if the stimulus is delayed to day 4, with animals inthis group being indistinguishable from those in the MI group, who didnot receive rIPost. Interestingly, when additional repeated rIPost wasgiven during the first 28 days after infarction, no further decrease ininfarct size was detected, however, there was additional protectionagainst adverse LV remodeling, which was closely associated withattenuated inflammatory responses, and less oxidative stress, comparedto those having a single early episode of post-conditioning.Furthermore, the protective effect of repeated rIPost was demonstrablydose-dependent, with significant additional benefits from daily rIPosttherapy when compared to rIPost delivered every 3 days during the 28follow up period. These functional benefits translated to improvedsurvival at 84 days, again with maximal benefit seen in the groupsubjected to daily post-conditioning for the first 28 days.

Ischemia reperfusion injury leads to excessive production of reactiveoxygen species (ROS) as well as decreased antioxidant activity^([23]).ROS generated upon reperfusion causes cellular damage with oxidation andperoxidation of membrane lipids with consequent “ROS induced ROSgeneration”^([24]) setting the scene for a cascade of local inflammatoryprocesses that contribute to further cellular injury during the days andweeks after an ischemia-reperfusion injury. Since the phenomenon ofischemic pre-conditioning was first described by Murry et al.^([25])extensive studies have been performed to elucidate the underlyingmechanisms by which pre and post-conditioning exert theircardioprotective effects. While the exact mechanisms are still not fullyunderstood, it is generally agreed that the attenuation of ROSgeneration^([26-28]) is of paramount importance in the protectionafforded by these strategies. Furthermore, it is well established thatcontinued ROS generation and inflammation is also pivotal in the processof post MI remodeling^([29,30]). Remote pre-, per- and post-conditioninginduced by limb ischemia have all been demonstrated to provide potentacute protection against myocardial damage in experimentalmodels^([5,14,15]) and in clinical trials^([31]). There also seems to bean effect on circulating monocytes, downregulating white cellproinflammatory pathways^([21,32]) and, when delivered daily for 10days, reducing neutrophil adhesion phagocytosis and proinflammatorycytokine responses. Our findings are consistent with reduced oxidativestress (reduced NF-kB phosphorylation and activation of TGFβ1/Smad2signaling), decreased inflammatory cell migration into the infarct zone(observed directly and as attenuated MDA concentration and 8-OHdGimmunostaining density) and reduced local inflammatory cytokinesignaling (reduced tissue MCP-1 expression, reduced circulating TNF-αand IL-1β levels). The modification of the local and circulatinginflammatory milleau is likely crucial to the chronic effects of chronicrIPost. Local chemokines such as MCP-1 are responsible for inducingrecruitment of mononuclear cells. Moreover, activated NF-κB pathways canalso up-regulate the target gene expression of TNF-α andIL-1β^([29,30,33]). This ‘anti-inflammatory’ effect is over and aboveinfarct size reduction, as there was no additional benefit of repeatedpost-conditioning compared with perconditioning alone in our studies.Clearly more focused experiments will be required to assess any causalrelationship between rIPost, local oxidative stress and circulatingcellular responses, but the overall effect of this stimulus, whenrepeated during the first 28 days after our experimental insult, toimprove remodeling in the form of LV dilation and dysfunction incombination with myocyte hypertrophy has obvious clinical relevance topost-MI recovery in humans.

In this regard, and similar to other remote conditioning protocols,there is capacity for our observations to translate rapidly to clinicaltrials. The facile nature of the remote stimulus by transient limbischemia has already led to positive clinical trials showing benefits ofremote pre-conditioning in adults and children undergoing cardiac andvascular surgery^([7]). Furthermore, the results of a RCT ofperconditioning in adults with evolving MI (4 cycles of 5 minutestransient limb ischemia followed by 5 minutes reperfusion prior toemergency PCI) were recently reported in abstract form^([34]). The earlyconditioning stimulus used in the current study is somewhat of a hybridof perconditioning and post-conditioning, as the conditioning stimulusstarted during ischemia, and continued during the early reperfusionperiod. As such, it perhaps better reflects a “real-life” period, butextends into the reperfusion period after successful PCI. Whether thesubsequent conditioning episodes are best described as post-conditioningor pre-conditioning is largely semantic, but we would caution that verylittle is known of the effects of chronic ischemic conditioning underany circumstances. Consequently, any clinical trial must includevigilant assessment for adverse, as well as beneficial effects ofchronic rIPost strategies.

CONCLUSION

In summary, we have shown that compared with a single episode of remoteperconditioning, chronic administration of remote ischemicpost-conditioning provides additional protection against pathologicalventricular remodeling which is independent of the effects on infarctsize, and improves survival, after MI. This dose-dependent protectionconferred was associated with improved oxidative stress, inflammatoryresponse and modulation of hypertrophic and fibrotic signaling.

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EQUIVALENTS

The foregoing written specification is considered to be sufficient toenable one ordinarily skilled in the art to practice the invention. Thepresent invention is not to be limited in scope by examples provided,since the examples are intended as mere illustrations of one or moreaspects of the invention. Other functionally equivalent embodiments areconsidered within the scope of the invention. Various modifications ofthe invention in addition to those shown and described herein willbecome apparent to those skilled in the art from the foregoingdescription. Each of the limitations of the invention can encompassvarious embodiments of the invention. It is, therefore, anticipated thateach of the limitations of the invention involving any one element orcombinations of elements can be included in each aspect of theinvention. This invention is not limited in its application to thedetails of construction and the arrangement of components set forth orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced or of being carried out in variousways.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including”, “comprising”, or “having”, “containing”, “involving”, andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

TABLE 1 Data obtained from each group rats to assess cardiac geometry,function, infarct size and hemodynamic changes. IR Parameter Sham MIsPost dPost rPost iPost Motality (dead rats/total number of ratsunderwent reperfusion injury) Day 4 0/21 6/28 3/24 5/26 3/23 2/22 Day 280/21 9/28 4/24 8/26 3/23 2/22 Echocardiographic data LVEDD 0.54 ± 0.130.74 ± 0.07* 0.63 ± 0.07^(#) 0.67 ± 0.09* 0.57 ± 0.07^(# ) 0.53 ±0.07^(#& ) (cm) LVESD 0.23 ± 0.06 0.53 ± 0.07*  0.40 ± 0.05*^(#)  0.46 ±0.05*^(#)  0.34 ± 0.04*^(#)  0.29 ± 0.04*^(#&) (cm) FS 57 ± 3  29 ± 3* 36 ± 7*^(#) 31 ± 3*^(&) 40 ± 3*^(# ) 45 ± 3*^(#& %) (%) Hemodynamic dataHR 404 ± 26  394 ± 22  402 ± 25  410 ± 23  405 ± 23   401 ± 25   (bpm)LVEDP 5.08 ± 0.61 19.45 ± 1.29*  14.03 ± 0.87*^(#) 18.42 ± 1.3*^(&  )12.96 ± 0.65*^(#&) 11.17 ± 0.84*^(#&%) (mmHg) dP/dt_(max) 5815 ± 253 2405 ± 347*  3247 ± 227*^(#) 2612 ± 335*^(& ) 4038 ± 284*^(#&) 4519 ±278*^(#&%) (mmHg/s) dP/dt_(min) 5043 ± 309  2117 ± 164*  2777 ± 246*^(#)2418 ± 360*^(& ) 3328 ± 240*^(#&) 3855 ± 270*^(#&%) (mmHg/s) Morphologydata LVMI 2.08 ± 0.34 3.25 ± 0.54*  2.73 ± 0.31*^(#) 3.01 ± 0.36* 2.51 ±0.32*^(#) 2.18 ± 0.28^(#& ) (mg/g) Infarct size NA/AAR 0 50.5 ± 4.11 35.63 ± 4.21^(# ) 48.13 ± 4.7   33.88 ± 3.52^(#  ) 31.88 ± 4.82^(#  )(%) (day4) IP 0 44.63 ± 3.66  29.27 ± 3.01^(# )  42 ± 4.54 28.5 ±3.46^(# ) 26.25 ± 4.43^(#  ) (%) (day28) All the data are expressed asmean ± SD. *denotes P < 0.05 vs Sham group; ^(#)P < 0.05 vs MI group;^(&)P < 0.05 vs sPost group; ^(%)P < 0.05 vs rPost group; LVEDD, leftventricular end-diastolic diameter; LVESD, left ventricular end-systolicdiameter; LVEDP, left ventricular end-diastolic pressure; LV, leftventricle; and BW, body weight.

1. A method comprising performing repeated remote ischemic conditioning(RIC) regimens on a subject after a myocardial infarction.
 2. The methodof claim 1, wherein the repeated RIC regimens are commenced within 1week or within 1 month of the myocardial infarction.
 3. The method ofclaim 1, wherein the subject has not undergone prior ischemicconditioning prior to the myocardial infarction.
 4. The method of claim1, wherein the subject has not undergone prior ischemic conditioningduring the myocardial infarction.
 5. The method of claim 4, wherein theprior ischemic conditioning is remote or local.
 6. The method of claim1, wherein the subject has undergone prior ischemic conditioning.
 7. Themethod of claim 6, wherein the prior ischemic conditioning occurredprior to the myocardial infarction.
 8. A method comprising performingrepeated remote ischemic conditioning (RIC) regimens on a subject aftera myocardial infarction, wherein the subject has experienced ischemicconditioning remotely or locally during the myocardial infarction.
 9. Amethod for reducing the incidence, delaying the onset, and/or reducingthe severity of heart dysfunction and/or heart failure comprisingperforming repeated remote ischemic conditioning (RIC) regimens on asubject during and after a myocardial infarction.
 10. A methodcomprising performing repeated remote ischemic conditioning (RIC)regimens on a subject having a myocardial infarction, wherein a firstRIC regimen is performed during the myocardial infarction and subsequentRIC regimens are performed at least every three days after the first RICregimen.
 11. A method comprising performing repeated remote ischemicconditioning (RIC) regimens on a subject having a myocardial infarction,wherein a first RIC regimen is performed during the myocardialinfarction and subsequent RIC regimens are performed daily after thefirst RIC regimen.
 12. The method of claim 10, wherein subsequent RICregimens are performed every two days after the first RIC regimen. 13.The method of claim 8, wherein the repeated RIC regimens are performedevery three days, every two days, or daily.
 14. The method of claim 8,wherein repeated RIC regimens are performed within a month after themyocardial infarction.
 15. The method of claim 9, wherein repeated RICregimens are performed within a month after the myocardial infarction.16. The method of claim 1, wherein the repeated RIC regimens comprisemore than one RIC regimen per day on one or more days.
 17. The method ofclaim 1, wherein the subject has not undergone balloon angioplasty or astent placement.
 18. The method of claim 1, wherein the subject ishuman.
 19. (canceled)
 20. The method of claim 10, wherein the first RICregimen is performed during reperfusion following ischemia associatedwith myocardial infarction.
 21. The method of claim 1, wherein at leastone RIC regimen of the repeated RIC regimens comprises at least fourcycles, each cycle comprising supra-systolic pressure and reperfusion.22-28. (canceled)